This file lists previously undocumented features available in the program.
These features may change or be discontinued at any time. Their use is
totally unsupported.
In prime.txt you can force the program to use different filenames for 7 files.
You can also change the working directory (identical to the -W command line
argument).
prime.ini=your_filename
worktodo.ini=your_filename
prime.log=your_filename
screen.log=your_filename
prime.spl=your_filename
results.txt=your_filename
WorkingDir=your_directory_name
Some options in prime.txt can be configured to have different values
at different times of the day using this syntax:
Option=setting
where setting is defined as
value OR value during list-of-times else setting
At present, only Memory, MaxHighMemWorkers, PauseWhileRunning, LowMemWhileRunning,
and PauseCheckInterval support this during/else syntax. Also note you can
no longer edit these options from the user interface. To use this feature,
you must manually edit the prime.txt file. An example in prime.txt:
Memory=500 during 1-5/17:30-24:00,1-5/0:00-8:30,6-7/0:00-24:00 else 200
The 1-5 and 6-7 refer to days of the week, with Monday=1 and Sunday=7. The
time portion refers to the hours of the day based on a 24-hour clock.
You do not need to specify days of the week (e.g. 1-7/0:00-8:00
is the same as 0:00-8:00). The above example lets the program use 500MB
during the week from 5:30PM to 8:30AM and all day on weekends. Otherwise
(weekdays from 8:30AM to 5:30PM), the program can use only 200MB.
There are some additional PRP proof controls that are not available in the
Resource Limits dialog box. In prime.txt,
PreallocateDisk=0 or 1 (default is 1)
will control whether disk space to hold the PRP proof residues is
allocated at the beginning of the PRP test to insure we do not run out
of disk space midway through the PRP test. In prime.txt,
MaxProofgenWaits=n (default is 48*60/5 = 48 hours)
Maximum number of 5 minute waits to execute when an error occurs during proof generation.
An error should only occur if a disk is full or offline. We hope the disk problem
will resolve itself within 2 days and proof generation can complete. In prime.txt,
ProofPower=x (x can be from 5 to 12)
ProofPowerAdjust=y (y can be from -2 to +3)
these override the selection of proof power based on temporary disk space available.
I don't see any reason to ever use these 2 settings. ProofPower sets the proof power to x.
ProofPowerAdjust is added to the proof power calculated based on temporary disk space.
If the proof power is higher than the optimal proof power, then the proof power is
reduced to the optimal proof power. Also available in the Primenet section of prime.txt,
ProofUploads=0 or 1 (default is 1)
UploadChunkSize=n (in MB, between 1 and 8)
DownloadRateLimit=n (in Mbps, default is 0 which means unlimited)
The first option can disable proof uploads. You will be responsible for taking the proof
files to a machine that is doing proof uploads. One might have a script that moves proofs
to a central machine for uploading -- to make sure at most one upload is in progress
at any time. You can choose the "chunk" size for uploading. The default is based
on your upload rate limit. Slow uploads are done 1MB at a time, fast uploads use
larger chunks. Rate limiting the downloads is available but I don't see the need
to ever use this as certification downloads are only around a dozen megabytes.
The program strives to use proof power 8 for large prime tests. This keeps certification
workload low. If temporary disk space resource limit will not let the program use proof
power 8, the program may simulate a higher proof power by creating a larger proof file.
For example, doing a power=7 proof on the first half of a PRP test and a second power=7
proof on the second half of a PRP test is equivalent to running a power=8 proof but using
half the temporary disk space and twice the upload bandwidth. In prime.txt, add
ProofPowerMult=1
to disable creating larger proof files to simulate a higher proof power. However,
if temporary disk space resources, proof file size resources, and upload bandwidth
resources are this limited it is strongly recommended switching to less demanding
work, such as double-checking.
There are also some options for controlling certification work. In prime.txt, add
CertWorker=n
CertMinExponent=x
CertMaxExponent=y
This lets you do certifications only on the specified worker number n. You can
also control the range of exponents you are willing to do certifications for.
You can control whether the program does extra error checking on every
iteration of a primality test. This runs a little bit slower. Windows
user can control the first of these options from the Advanced Menu.
Add one or both of these lines to prime.txt to control these options:
ErrorCheck=0 or 1
SumInputsErrorCheck=0 or 1
The first line controls "ROUNDOFF > 0.4" error checks, the second line
controls "SUM(INPUTS) != SUM(OUTPUTS)" error checks available in
pre-AVX FFTs (which makes it pretty much obsolete).
You can control how the "count of errors during this test" message
is output with every screen update. These messages only appear if
possible hardware errors occur during a test. In prime.txt set:
ErrorCountMessages=0, 1, 2, or 3
Value 0 means no messages, value 1 means a very short messages, value 2
means a longer message on a separate line, value 3 means a very long message
possibly on multiple lines. Default value is 3.
You can control how often Jacobi error checking is run. Default is 12 hours.
If a Jacobi test takes 30 seconds, then the default represents an overhead of
30 / (12 * 60 * 60) or 0.07% overhead. Each Jacobi test has a 50% chance of
discovering if a hardware error has occurred in the last time interval. In prime.txt:
JacobiErrorCheckingInterval=N (default is 12)
where N is in hours.
You can control how many save files are kept that have passed the Jacobi error check.
This value is in addition to the value set by the NumBackupFiles setting. So if
NumBackupFiles=3 and JacobiBackupFiles=2 then 5 save files are kept - the first three
may or may not pass a Jacobi test, the last two save files have passed the Jacobi error
check. In prime.txt:
JacobiBackupFiles=N (default is 2)
You can disable Jacobi error checking which has a 50% chance of catching
hardware errors. You might do this if you are running the first LL test and
double-checking LL test concurrently. In prime.txt
JacobiErrorCheck=0 or 1 (default is 1)
You can disable printing Jacobi error-checking messages using this prime.txt entry:
SilentJacobi=0 or 1 (default is 0)
You can force the Options/CPU dialog to display times using AM/PM or
a 24-hour clock format. Otherwise, the program will make its best guess
as to the proper format. Add this line to prime.txt:
AMPM=n
where n is 1 for AM/PM formatting and n is 2 for 24-hour formatting.
You can adjust how many decimal digits of precision are displayed
in lines output to the screen. In prime.txt enter a value between 0 and 6:
PercentPrecision=n
You can choose whether the program uses the high resolution system clock, the
standard system clock, or the read timestamp counter instruction (RDTSC) to
time events. By default the program uses the high resolution system clock if
available. Choose one of these values for n (default is 1):
0 - use the system clock.
1 - use RDTSC but do not output clock counts.
2 - use RDTSC and output clock counts.
The above values will only have an effect if a high resolution system clock
is not available. You can force the program to bypass the high resolution clock
by adding 10 to one of the values above. In prime.txt, enter
RdtscTiming=n
You can alter the way the program outputs timings. In prime.txt set:
TimingOutput=n
Where n=1 for seconds with 3 digits of precision, n=2 for milliseconds
with 1 digit of precision, n=3 for milliseconds with 2 digits of precision,
n=4 for milliseconds with 3 digit of precision.
You can change the formatting of date and time to the screen and logfiles.
In prime.txt:
TimeStamp=n (default is 1)
TimeStampUTC=x (default is 0)
TimeStampFormat=s
LogTimeStamp=n (default is 1)
LogTimeStampUTC=x (default is 0)
LogTimeStampFormat=s
Where x=0 is local time and x=1 is UTC time. The default format (n=1) for
screen output is Mon d hh:mm (e.g. Feb 8 12:34) and for logfiles is
Day Mon dd hh:mm:ss yyyy (e.g. Thu Feb 08 12:34:56 2024). Other n values
are n=0 turns output off, n=2 is the default screen output with seconds,
n=3 is time only without seconds, n=4 is time-only with seconds,
n=5 is YYYY-MM-DD HH-MM, n=6 is YYYY-MM-DD HH:MM:SS, n=7 means use the
TimeStampFormat=s or LogTimeStampFormat=s value as a format string for strftime.
See https://en.cppreference.com/w/cpp/chrono/c/strftime for formatting details.
You can have the timings that are output to the screen be cumulative
(from program restart or start of a new exponent) rather than resetting
after each screen output (ClassicOutput=1 only). Add this line to prime.txt:
CumulativeTiming=1
You can change the interval between outputs of the timestamp to the results.txt file
ResultsFileTimestampInterval=n
If n is zero, the timestamp will never be output. Otherwise the timestamp will be
written no more frequently than every n seconds. Default for n is 300 which is 5 minutes.
You can revert to the "classic" style output for worker windows doing
Lucas-Lehmer and PRP tests. This classic style does not display the
ETA. This style was in use prior to version 28.5. In prime.txt:
ClassicOutput=0 or 1 (default value is 0)
You can output the maximum round off error seen thusfar in the
worker windows when doing LL or PRP tests.
OutputRoundoff=0 or 1 (default value is 0)
You can reset the maximum round off error seen thusfar after each time
the maximum round off is output.
CumulativeRoundoff=0 or 1 (default value is 1)
You can update the title more frequently than the lines are output to the
worker window. This feature, only useful in Windows, allows you to keep
track of progress in the tray icon or window title without "cluttering up"
the worker window. In prime.txt:
TitleOutputFrequency=n (default value is 1)
The title will update n times more frequently than the worker window.
When workers are testing wildly different numbers, such as ECM on a small
Mersenne number in one window and an LL test on a 100 million digit number
in another window, then the "iterations between screen outputs" setting will
cause the windows to output at wildly different rates. You can workaround
this in prime.txt:
ScaleOutputFrequency=0 or 1 (default value is 0)
If you set this to 1, then "iterations between screen outputs" will be
automatically scaled so that windows produce output at roughly the same rate.
An LL test on M50,000,000 will not scale at all, ECM on a small number will
scale to a much larger value and an LL test on a 100 million digit number
will scale to a much smaller value.
The program normally will not start any calculation until 90 seconds after
a reboot. This is done so that your normal boot up procedure can be as
fast as possible. You can control how long this delay is by adding this
line to prime.txt, where n is the number of seconds to sleep:
BootDelay=n
Some machines report much better timings if the workers stagger
their starts. This was first noticed on Core i7 machines running Windows.
Presumably staggering starts improves timings due to each worker allocating
contiguous memory. You can control how long the program waits between
starting each worker. In prime.txt, enter:
StaggerStarts=n
where n is the number of seconds to wait. The default is 5 seconds.
The program supports many different code paths for PRP/LL testing depending on
the CPU type. It also has a few different factoring code paths. You can
force the program to choose a specific code path by setting the proper
combination of these settings in prime.txt:
CpuSupportsRDTSC=0 or 1
CpuSupportsCMOV=0 or 1
CpuSupportsPrefetch=0 or 1
CpuSupportsSSE=0 or 1
CpuSupportsSSE2=0 or 1
CpuSupports3DNow=0 or 1
CpuSupportsAVX=0 or 1
CpuSupportsFMA3=0 or 1
CpuSupportsFMA4=0 or 1
CpuSupportsAVX2=0 or 1
CpuSupportsAVX512F=0 or 1
This shouldn't be necessary though as the program uses the CPUID instruction
to see if the CPU supports these features.
The program also supports different code paths for LL testing on a Pentium 4
based on the size of the L2 cache. You can explicitly specify the L2 cache
size although this shouldn't be necessary since the program uses the CPUID
instruction to determine the L2 cache size. In prime.txt enter:
CpuL2CacheSize=128 or 256 or 512
CpuL2CacheLineSize=32 or 64 or 128
CpuL2SetAssociative=4 or 8
The program automatically computes the number of CPU cores, hyperthreading, and speed.
This information is used to calculate how much work to get. In the unlikely event
the program did not correctly figure out your CPU information, you can override
the info in prime.txt:
NumCores=n
CoreXXXNumThreads=1 or 2
CoreXXXRanking=0 or 1
CpuSpeed=s
Where n is the number of physical cores -- not logical cores created by hyperthreading.
XXX is the zero-based physical core number (see hwloc output in results.bench,txt).
Choose NumThreads of 1 for non-hyperthreaded or 2 (or more) for hyperthreaded.
Choose Ranking of 0 for efficiency cores and 1 for performance cores.
Finally, s is the speed in MHz.
The program sometimes performs work from worktodo.txt out-of-order.
(1) Certification work is done quickly as these assignments have a very short
expiration period.
(2) Any necessary trial factoring and P-1 testing on exponents reserved for a
prime test can be done early. This option exists for for users without an
always-on Internet connection. If early factoring finds a factor, the server
can be contacted and another exponent reserved avoiding the possible scenario
where a prime test for the first worktodo.txt line completes, a factor is quickly
found for the second line in worktodo.txt and the computer now sits idle until
the server can be contacted. This behavior can be confusing, especially
to newcomers.
The option to control what work can be done early is in prime.txt:
SequentialWorkToDo=n (default is -1)
If n is 1, work will never be done out of order, You will not get certification
assignments. If n is -1, only certification work will be done out of order.
If n is 0, certification and early factoring will be done out of order.
The program will restrict how many exponents can be added to worktodo.txt to 15.
To override this, change prime.txt:
MaxExponents=n
By default, ECM ignores B2=100*B1 (this is what PrimeNet assigns) and calculates
the optimal B2. You can override this behavior in prime.txt:
ECMBestB2=0
Similarly, P-1 ignores B2 when the worktodo.txt entry contains information on how much
trial factoring has been done. The optimal B2 value occurs when incremental P-1 effort
invested in either a large B1 or larger B2 results in the same increase in the chance
of finding a factor. As a refresher, P-1 worktodo.txt entries for k*b^n+c are in
this format: Pminus1=k,b,n,c,B1,B2[,how_far_factored][,"factors"]
Override this behavior, using the B2 from worktodo.txt, with this prime.txt entry:
Pminus1BestB2=0
And P+1 can also override the B2 value in worktodo.txt. Turn this feature off in
prime.txt with:
Pplus1BestB2=0
You can increase the ECM B1 value assigned by the server using this prime.txt setting:
ECMBoundsMultiplier=n (default is 1)
Ordinarily a B1 value significantly larger than suggested is a little less efficient
in advancing the ECM "T-level". However, the program may be better able to put large
amounts of memory to good use with larger B1 values. WARNING: changing this setting
in the middle of a set of ECM curves will delete the ECM save file.
For P-1 and ECM you can increase the number of cores used in stage 2 vs. stage 1.
In prime.txt, set:
Stage2ExtraThreads=n (default is zero)
This can be useful on machines with lots of cores. For example, if you have a 16-core
machine and want to do ECM on Mersenne numbers below M100000. These numbers are so
small that multi-threading in stage 1 is not possible. Therefore, you want to run
16 workers each doing ECM. Stage 2 is most efficient if it uses all available memory.
However, a single worker running stage 2 on one core cannot keep up with 16 cores
running stage 1. Suppose 4-threaded stage 2 can keep up with 13 workers running stage 1.
Set up prime95 to run 13 workers each using one core. Set Stage2ExtraThreads=3.
The first worker to reach stage 2 will grab the 3 extra workers to quickly finish stage 2.
Other workers reaching stage 2 during this time will wait for the first worker to finish stage 2.
Eventually, the 13 workers will stagger such that there workers are not often idle.
The three cores used only in stage 2 will be used most of the time. This is not a
completely optimal solution, but it can be very, very effective.
For P-1 and ECM stage 2 to accurately choose optimal B2 bounds as well as whether prime pairing
stage 2 is more appropriate than polynomial multiplication stage 2, the program must
accurately estimate stage 2 vs. stage 1 runtime. The default formula will not work for
all current and future CPUs, cache, and memory configurations. Hopefully, the default
formula is "good enough". You can correct for errors in the program's default formula
with two adjustments in prime.txt:
Pm1PairRatioAdjust=n (default is 1.0)
Pm1PolyRatioAdjust=n (default is 1.0)
EcmPairRatioAdjust=n (default is 1.0)
EcmPolyRatioAdjust=n (default is 1.0)
One adjustment is for stage 2 using prime pairing and the other is for stage 2 using
polynomial multiplication. When P-1 starts stage 2 the estimated stage 2 vs. stage 1
runtime is output (example: "Estimated stage 2 vs. stage 1 runtime ratio: 1.034").
Set Pm1____RatioAdjust to the actual ratio divided by the estimated ratio times the
current RatioAdjust setting. For example, if stage 1 took 5000 seconds and stage 2 took
8000 seconds the actual ratio is 1.6, set the adjustment to 1.6 / 1.034 * 1.0 = 1.547.
These settings are likely to be deprecated and replaced with the settings in the next
paragraph.
For P-1 and ECM stage 2 to accurately choose optimal B2 bounds as well as whether prime pairing
stage 2 is more appropriate than polynomial multiplication stage 2, the program must
accurately estimate stage 2 vs. stage 1 runtime. The default formula will not work for
all current and future CPUs, cache, and memory configurations. The program auto-adjusts
for estimated vs. observed runtimes. Auto-correction can be disabled and set manually
with these prime.txt settings:
Pm1Stage2AutoAdjust=0 or 1 (default is 1)
Pm1Stage2RatioAdjust=n (default is 1.0)
EcmStage2AutoAdjust=0 or 1 (default is 1)
EcmStage2RatioAdjust=n (default is 1.0)
The AutoAdjust setting can be used to disable or enable the program auomatic adjustment
of the Stage2RatioAdjust setting. The Stage2RatioAdjust setting multiplies the program's
default estimate of stage 2 runtime so that the estimate of stage 2 runtime vs. stage 1
runtime is hopefully more accurate leading to more optimal B2 bounds selection.
In P-1, P+1, and ECM stage 2 a pairing map is allocated for recording prime pairs. The default
maximum size for this map is 250MB. Only very large B2 values need a map this large.
You can change the maximum map size with this poorly named prime.txt entry:
MaximumBitArraySize=n (default is 250)
Values from 1 to 2000 are supported.
For ECM stage 1, one can use either Edwards curves or Montgomery curves. One can also
specify whether to use Edwards stage 1 or Montgomery stage 1. In prime.txt, add
MontgSigma=0 or 1 (default is 0 for most setttings of DictionaryMemory)
MontgStage1=0 or 1 (default is 0 for Edwards curves, 1 for Montgomery curves)
Using Edwards stage 1 on a Montgomery curve makes little sense as the program will
have to use convert the Montgomery curve to a twisted Edwards curve.
For Edwards ECM stage 1, you can control how much memory can be used. In prime.txt, add
DictionaryMemory=n (default is 256)
where n is MB.
For Edwards ECM stage 1, you can control which doubling algorithm to use. In prime.txt, add
EdDblAlgo5=0 or 1 (default is 0)
EdDblAlgo6=0 or 1 (default is 1)
There are 3 algorithms (4, 5, and 6). Algorithm 4 and 6 are similar and unlikely to perform
much differently. I've seen cases where algorithm 5 is a little faster.
For Montgomery ECM stage 1, the program examines several different Lucas-chains looking
for the shortest. For ECM on very small numbers, it may be beneficial to reduce the search
effort as the work saved is pretty small. For ECM on larger numbers, it might pay to increase
the search effort. I have not studied the optimal search effort, so the current default of 7 is
a complete guess. To change the search effort, add this to prime.txt:
PracSearch=n (default is 7)
Values from 1 to 50 are supported.
By default, ECM will stop when a new factor is found. You can have ECM stop or
continue searching for factors by using a value of zero or one in prime.txt:
ContinueECM=n
You can skip the GCD in stage 1 of P-1 and P+1 factoring with this prime.txt setting:
Stage1GCD=n (default is 1)
For P+1, set n to one to do a GCD after stage 1, set n to 0 or -1 to skip stage 1 GCD.
For P-1, a stage 1 GCD is very, very cheap. Set n to 1 or 0 to do the cheap stage 1 GCD,
set n to -1 to skip the stage 1 GCD. This all tranlates to:
n=1, always do stage 1 GCD
n=0, do stage 1 GCD if it is cheap
n=-1, never do stage 1 GCD
You can have the program generate save files every n iterations. The files
will have a .XXX extension where XXX equals the current iteration divided
by n. In prime.txt enter:
InterimFiles=n
You can have the program output residues every n iterations. The default
value is the InterimFiles value. In prime.txt enter:
InterimResidues=n
If doing P-1 with a very large B1, the program uses about 47MB of memory to
pre-calculate the product of all small primes below 250 million. The primes above
250 million are processed using a somewhat slower method. You can elect to use
more memory to move the 250 million threshold higher. In prime.txt enter:
MaxStage0Prime=n (n is in millions, default is 250, max is 2000)
By default P-1 work does not delete the save files when the work unit completes.
This lets you run P-1 to a higher bound at a later date. You can force
the program to delete save files by adding this line to prime.txt:
KeepPminus1SaveFiles=0
By default P+1 work does delete the save files when the work unit completes.
Should you want to run P+1 to a higher bound at a later date. You can force
the program to keep save files by adding this line to prime.txt:
KeepPplus1SaveFiles=1
You can force the program to skip the trial factoring step prior to
running a Lucas-Lehmer or PRP primality test. In prime.txt add this line:
SkipTrialFactoring=1
You can do "optimal" P-1 factoring of k*b^n+c by adding lines to worktodo.txt:
Pfactor=k,b,n,c,how_far_factored,num_primality_tests_saved
For example, Pfactor=1,2,10000157,-1,64,2.0
You can limit which exponents PrimeNet will assign to you. In prime.txt, add
GetMinExponent=x
GetMaxExponent=y
Assignments from PrimeNet will be on exponents between x and y.
You can reduce the number of times worktodo.txt is read and written by
setting in prime.txt:
WellBehavedWork=1
This feature is useful for BIG worktodo.txt files that are modified often due
to worktodo entries that don't take much time to complete. The worktodo.txt
file will be written at most once every half hour. A side benefit the initial
reading of worktodo.txt is much faster. The downside is a computer crash may
leave you with a worktodo.txt file that contains some entries for work that
has already completed.
Editing the worktodo.txt file while the prime95/mprime is running is not always safe.
Rather than exiting prime95/mprime, editing worktodo.txt, and restarting, you can
create a worktodo.add file. Prime95/mprime will periodically look for worktodo.add
and append the entries from each "[Worker #]" section. Then the worktodo.add file
will be deleted.
In Advanced/Time, you can enter a value between 9994 and 9999 for the
exponent to run a QA script. The QA file looks like this:
64511,0,400,99999999,3389BC878321980A
Where the first value is the exponent, the second value is the FFT size where
zero means use the default FFT size. The third value is the number of
iterations to run. The fourth value is the shift count (if the shift count
is greater than the exponent a random shift count is used). The final value
is the expected 64-bit residue.
The dialog box values between 9994 and 9999 force slightly different
code to run. 9999 and 9998 run straightforward squaring code, 9998 differs
by gathering some standard deviation data. 9997 does squarings also
but exercises the general purpose add/sub/mul routines too. 9996 does
operations typical during ECM - the final residue won't match but the
convolution error data can be useful. 9994 and 9995 probably blow up.
Advanced/Time of exponent 9990 forces reading of a file called
factors. The program then tries to refind each factor using the
factoring code. This is not an efficient way to verify factors as it
goes through the entire sieving process and trial factoring many
potential factors.
You can control whether a torture test using lots of RAM alternates between
running in-place and using lots of RAM with this prime.txt setting:
TortureAlternateInPlace=0 or 1 (default is 1)
The torture test defaults to alternating to try different scenarios that might cause
a hardware failure. Turning alternating off may do a better job of stressing all RAM.
The program normally does round-off error checking every 128 iterations.
When you are testing an exponent near the limit of an FFT length, the program
does this error checking every iteration.
NearFFTLimitPct=value
The default value is 0.5 (if the exponent you are testing is within 0.5% of the
maximum exponent that can be tested using the current FFT length, then the
extra error checking is performed). A value of 0.0 will turn off this extra
error checking.
You can tune trial factoring performance with several prime.txt settings. Probably
only the first parameter below is worth tuning:
MaxTFSievePrime=x (default is 155000 on AVX512 CPUs, 145000 on FMA CPUs, 1000000 otherwise)
The TF code uses a small prime sieve to eliminate composite trial factors.
Set x to the maximum small prime used by this sieve. MaxTFSievePrime is limited
to the range of 5,000 to 100,000,000.
ThreadsPerTFPool=n (default is number of hyperthreads)
When multithreading, set n to the number of threads to group together in a "pool".
Pooling ensures that both sieving and trial factoring will be done by threads within
the same pool. Thus, if the threads share a cache, locality is increased. For example,
on Knights Landing the best setting is 8 because 2 cores with 4 hyperthreads each
share an L2 cache.
PercentTFSieverThreads=y (default is 50)
When multithreading TF, set y to be the percentage of threads in each pool that can be
running the small prime sieve. NOTE: If y is set to 100, then pooling is turned off.
That is, each thread sieves and then immediately TFs. While this offers perfect locality,
it gives slightly worse performance and I cannot explain why. My best theory is that
pooling improves usage of the instruction cache.
UseMaxSieverAllocs=0, 1, 2,or 3 (default is 3)
If UseMaxSieverAllocs is 1 then at least 7 sievers will be allocated, resulting
in a 14% reduction in single-threaded sieving. If UseMaxSieverAllocs is 2 then at
least 60 sievers will be allocated, resulting in a further 9% reduction in sieving.
If UseMaxSieverAllocs is 3 then at least 720 sievers will be allocated, resulting in
a further reduction of 7%. The downside is more memory is required and initialization
of each of the 16 factoring passes is slower. Allocating a lot of sievers can be
detremental when factoring to low bit levels.
AlternateTFSieveCount=z (default is 9)
On AVX2 and AVX512 cpus, the code can sieve for small primes using either traditional x86
instructions or using AVX2/AVX512 instructions. As sieve primes get larger, the x86 code
is faster than the AVX2/AVX512 code. Set z to the number of blocks of small primes to use
the AVX2/AVX512 code path. On my AVX2 Skylake cpu the optimal block count is 9. Using too
large a value here can result in memory corruption depending on the MaxTFSievePrime setting.
You can control how many CPU cores and hyperthreads are used in Advanced/Time.
Put these line in prime.txt:
AdvancedTimeMinCores=n (default 1)
AdvancedTimeMaxCores=n (default all cores)
AdvancedTimeCoresIncrement=n (default 1)
AdvancedTimeMinHyperthreads=n (default 1)
AdvancedTimeMaxHyperthreads=n (default is number of hyperthreads supported by each core)
You can disable the display of every iteration's timing when using Advanced/Time
leaving just the ending summary. Useful for machines with lots of cores.
Put this line in prime.txt:
PrintTimedIterations=0
You can output some informational message on ECM/P-1/P+1 estimated pairing percentages
to compare with actual pairing percentages. Add to prime.txt:
Stage2Estimates=1
You can also output more detailed P-1 stage 2 information with this prime.txt entry:
PolyVerbose=1
P-1 stage 2 can compress data to create bigger polynomials. In prime.txt, set
Poly1Compress=0,1,2 (default 2)
where 0 is no compression, 1 is quick compression gaining about 1.6%, 2 is serious
compression gaining about 12%.
LINUX/FREEBSD ONLY: When mprime runs out of work to do, it normally loops waiting for the
server to assign more work. This prime.txt option can be used to have mprime exit
when all workers runs out of work. Note this probably only makes sense when UsePrimenet=0
or when UsePrimenet=1 and QuitGIMPS=1.
ExitWhenOutOfWork=n
where n is the number of seconds to wait before exiting. I recommend setting n to 86400 or
higher to give mprime time to send the last results and upload proof files to the server.
WINDOWS ONLY: When Tray Icon or No Icon is selected the "X" at the right of
the title bar will minimize rather than exit. You can make the program exit
if you prefer. In prime.txt set:
ExitOnX=1
Most FFT sizes have several implementations. The program uses throughput benchmark
data to select the fastest FFT implementation. The program assumes all CPU cores
will be used and all workers will be running FFTs. This can be overridden
in gwnum.txt:
BenchCores=x
BenchWorkers=y
An example: a 4-core computer running 4 total workers with 3 workers configured for
LL testing and one configured for trial factoring. In this scenario, the trial factoring
worker does not use much memory bandwidth. You might get a faster FFT implementation
selected by setting BenchCores=3 and BenchWorkers=3. Of course, you'll need to generate
throughput benchmark data for the 3 cores / 3 workers combination.
One can adjust FFT crossover points up or down. In prime.txt use the setting:
ExtraSafetymargin=n (recommend n between 0.01 and -0.01)
For each FFT size, the program uses a pre-calculated maximum number of bits that can be
safely stored in each FFT word. This setting reduces the pre-calculated maximum
by n bits. If n is a positive number, the maximum bits per FFT word is reduced, which
reduces round off errors. If n is a negative number, the maximum bits per FFT word is
increased, which increases round off errors. Values of n below -0.025 could be pretty
dangerous.
Alexander Kruppa wrote some code that allows the output of ECM stage 1 to
be passed to Paul Zimmermann's more efficient GMP-ECM stage 2. This program
is usually faster in stage 1. You can activate this feature by entering
GmpEcmHook=1
in prime.txt. Then select ECM bound #2 between 1 and bound #1. Results.txt
will contain data that can be fed to GMP-ECM for stage 2.
In rare cases, users have reported the program can interfere with the
performance of some programs such as disk defragmenters and some games.
You can pause the program automatically when these programs are running by
adding this line to prime.txt:
PauseWhileRunning=prog1[n1],prog2[n2],etc
The [n1], [n2] values are optional and indicate the number of workers
to pause when prog1 and prog2 are running. The default value for n1 and n2
is to pause all workers. Note that the program will pause if the program
name matches any part of the running program's file name. That is "foobar"
will match "c:\foobar.exe", "C:\FOOBAR\name.exe", and even "C:\myfoobarprog.exe".
Also, if prog1 is "*" the program will pause no matter what. Examples:
PauseWhileRunning=*[1] during 6-7/2:00-3:00
PauseWhileRunning=* during 23:00-24:00 else decomp[1],mygame[2]
The first example pauses one worker on Saturday and Sunday between
2AM and 3AM. The second example pauses all workers between 11PM and 12AM and
pauses 1 worker if decomp is running and 2 if mygame is running.
LowMemWhileRunning is similar to PauseWhileRunning. This option does not
allow workers to use a lot of memory. This example in prime.txt will make
sure the program is using the minimum amount of memory possible while
photoshop is running:
LowMemWhileRunning=Photoshop
By default, the program will check the PauseWhileRunning list every 10 seconds.
You can adjust the time period with this prime.txt setting:
PauseCheckInterval=n
where n is the number of seconds between checking which programs are running.
LINUX/FREEBSD/APPLE ONLY: In prime.txt you can have mprime suspend one worker
when the system load gets above a threshold. This can improve system responsiveness
by freeing up memory that mprime is currently using. Mprime bases
its decisions using the first average displayed by uptime. In prime.txt, set
MaxLoad=a
MinLoad=b
PauseTime=c
For example, if MaxLoad is set to 4.5, mprime will suspend a worker whenever the
load average gets above 4.5. If MinLoad is set to 3.1, then mprime will
resume one worker when the load average goes below this value. Set PauseTime
to how often you want the program to check the load average. This value
is in seconds.
Normally, the program will unreserve an exponent if it is scheduled to start
thirty days after the Test/Primenet Days of work to get value and there are more
than four exponents queued up for the worker. You can adjust the days interval
by setting in prime.txt:
UnreserveDays=n (default 30)
where n is the number of days. You can also adjust the number of protected
exponents in each worker with this setting in prime.txt:
UnreserveExponents=m (default 4)
where m is the number of protected exponents. You should increase one or both of
these values if you are loading up worktodo.txt with a large amount of work and
do not want any of the work to be unreserved.
WARNING: There have been several reports of a bug in prime95's calculations for
UnreserveDays. Thus, we recommend using UnreserveExponents to prevent unexpected
unreserving of work,
LINUX ONLY: Mprime supports 4 different ways of checking if your computer
is connected to the internet. Set RouteRequired=n in [PrimeNet] section
of prime.txt. The following values of n are supported. The last entry is
what happens if RouteRequired is not given.
0: Assume computer is always connected
1: Assume connected if there is an entry in /proc/net/route
other than for the loopback device.
2: Assume connected if there is an entry in /proc/net/route
with a netmask of 00000000.
none: Same as 2 except that if /proc/net/route is unreadable
mprime assumes computer is connected.
If you are running on a laptop or in a hot room and you want to slow the
program down to reduce heat, then you can add this line to prime.txt:
Throttle=n
where n is the percentage of time the program should run. For example,
Throttle=40 means the program will run 40% and be idle 60% of the time.
Since P-1,P+1,ECM stage 2 runs faster with more memory available you can have the
program only run stage 2 at night when more memory is available. In
prime.txt set:
OnlyRunStage2WithMaxMemory=1
You can capture screen output in a screen.log file. Add this line to prime.txt
to change the default:
ScreenLog=n (default 0)
where 0 means no logging, 1 means log everything. Alernatively, one can fine tune
what is logged with any combination of 2 = log worker windows, 4 = log communication
window, 8 = log main window, 16 = no prefix on output lines.
You can control the maximum prime.log file size. The default is 2MB. Add
this line to prime.txt to change the default:
MaxLogFileSize=n
You can use the old sockets communication code instead of the robust CURL library.
Add this line to the [PrimeNet] section of prime.txt:
UseCURL=0
When using CURL, you can control whether the program automatically tries again
without using the proxy server when a request fails using the proxy server.
In the [Primenet] section of prime.txt enter:
TryNoProxyAfterProxyFailure=0 or 1 (default 1)
This feature is new in 29.5. Prior versions essentially implemented
TryNoProxyAfterProxyFailure=0
When not using CURL , you can control what type of URLs are used to contact the
PrimeNet server. In the [Primenet] section of prime.txt enter:
UseFullURL=n
where n is 0 for use relative URLs, 1 for use full URLs, 2 for try full URL
and if an error is returned try a relative URL. The default setting is 2.
Note that a full URL is always sent when using a proxy server.
When not using CURL and using a proxy server, the program sends the port number
in http strings. That is the ":80" in "http://mersenne.org:80/cgibin_text".
At least one proxy server only works if the ":80" is not present. In this case, set
SendPortNumber=0
in the [Primenet] section of prime.txt file.
When not using CURL, you can add additional information to the HTTP request
sent to the server. This might be useful in some tough firewall setups.
In the [Primenet] section of prime.txt enter:
OtherGetInfo=string
where string is any text up to 256 bytes.
The benchmarking dialog box lets you control many options, yet there are a few
more that are only available using the settings below:
BenchOutputTopology=0 or 1 (default is 1)
BenchOddWorkers=0 or 1 (default is 1)
BenchDummyWorkers=0 or 1 (default is 0)
BenchOutputTopology can be used to disable printing the machine topology in results.txt.
BenchOddWorkers can be used to disable throughput benchmarks when number of cores is not
a multiple of the number of workers (e.g. 3 cores on 2 workers).
BenchDummyWorkers is used to enable starting dummy workers while benchmarking.
The theory is that keeping the other CPU cores busy will prevent "turbo boost" from kicking in.
This may lead to more consistent benchmarks that are more indicative of what will happen running
this program in a real-world, all-cores-busy environment. Option not available in throughput
benchmarks.
Since benchmark dialog boxes now accept a comma separated list of ranges, this next setting is
now obsolete. When benchmarking on CPUs with lots of cores, the volume of output can be overwhelming.
You can limit which core counts are benchmarked using the prime.txt settings below:
BenchMinCores=n (default 1)
BenchMaxCores=n (default all cores)
BenchCoresIncrement=n (default 1)
Similarly, for thoughput benchmarks, these prime.txt settings can reduce output:
BenchMinWorkers=n (default 1)
BenchMaxWorkers=n (default all cores)
BenchWorkersIncrement=n (default 1)
The program automatically runs benchmarks to aid in optimal FFT selection. It looks
at worktodo.txt for upcoming exponents to test and the amount of benchmarking
already done to decide if more benchmarks are needed. You can disable this feature
by adding to prime.txt:
AutoBench=0
If you want to run the program on several machines this is typically done
by carrying the program and files around on portable media such as a
USB memory stick. In this case, you need to defeat the program's
automatic detection of hardware changes. To do this, in prime.txt set
FixedHardwareUID=1
Adding 32 to the MergeWindows value in prime.txt suppresses screen output
of the "Comm thread", "Main thread", "Work thread" prefix.
The Memory=n setting in prime.txt refers to the total amount of memory the
program can use. You can also put this in the [Worker #n] section to place
a maximum amount of memory that one particular worker can use.
You can set MaxHighMemWorkers=n in prime.txt. This tells the program how
many workers are allowed to use lots of memory. This occurs doing stage 2
of P-1, P+1, or ECM. Default is 1.
You can set a threshold for what is considered lots of memory in MaxHighMemWorkers
calculations. In prime.txt, set:
HighMemThreshold=n (default is 250)
The value n is in MB.
You can change the amount of information the program outputs while setting affinities.
AffinityVerbosity=0 or 1 (default is 1)
AffinityVerbosityTorture=0 or 1 (default is 0)
AffinityVerbosityTime=0 or 1 (default is 0)
AffinityVerbosityBench=0 or 1 (default is 0)
These settings are made in prime.txt. Zero for less output, one for more output.
The first setting is for all normal work (LL, TF, ECM, P-1, P+1, PRP). The others
are for torture testing, Advanced/Time, and benchmarking.
One user reported problems with setting affinity on machines with more than 64 cores.
Though this problem has been addressed, the following options may prove helpful
if similar issues occur in the future:
EnableSetPriority=0 or 1 (default is 1)
EnableSetAffinity=0 or 1 (default is 1)
Set these options in prime.txt
One can override the default affinity settings with the Affinity= option in prime.txt.
Suppose you want to change which logical CPUs the second worker uses. Here are some
example lines you might add to the "[Worker #2]" section of prime.txt (the logical CPUs use
the zero-based numbering scheme for PU# returned by hwloc which you can see in results.txt
by doing a benchmark):
Affinity=3,6,9
Run main worker on logical CPU #3, run two aux threads on logical CPUs #6 & #9
Affinity=3-4,5-6
Run main worker on logical CPUs #3 & #4, run aux thread on logical CPUs #5 & #6
Affinity={3,5,7},{4,6}
Run main worker on logical CPUs #3, #5, & #7, run aux thread on logical CPUs #4 & #6
Affinity=(3,5,7),(4,6)
Run main worker on logical CPUs #3, #5, & #7, run aux thread on logical CPUs #4 & #6
Affinity=[3,5-7],(4,6)
Run main worker on logical CPUs #3, #5, #6, & #7, run aux thread on logical CPUs #4 & #6
In the prime.txt file, the DaysBetweenCheckin value can be set to any value
between 0.04 and 7.0. Some SeventeenOrBust users want to send updates hourly.
To attempt using 2MB pages under Windows and Linux, add this line to prime.txt:
UseLargePages=1
My experience has been maybe a 0.5% speed improvement, but sometimes I get worse timings.
It may well be that any benefit is within the margin of error in obtaining accurate timings.
Warning: My understanding is that these pages will never be swapped out in Windows (and will
be slower to swap in Linux). Thus, using this option could negatively impact the performance
of other applications. Also, wasted space at the end of each page (1MB on average) can reduce
the number of temporaries that can be allocated in stage 2 of P-1/P+1/ECM, negating any benefits.
In Windows you'll need to have the "Lock Pages in Memory" privilege to use this option.
Multithreaded FFTs by default use mutexes/signals/events to coordinate threads. When a thread
runs out of work it relinquishes control of the thread to the OS. Alternatively, prime95/mprime
can use "spin loops" where the thread busy waits for other threads to finish up. Many, including
Linus Torvalds, believe spin waits in user space is evil. Read up on the hazards of spin waits
at https://www.realworldtech.com/forum/?threadid=189711&curpostid=189723 and elsewhere.
That said, a system primarily dedicated to running prime95/mprime could see a minor benefit.
In prime.txt, set
SpinWait=n (default is 0)
Setting n to one tells the worker's main thread to spin wait on helper threads to finish up.
A setting above one also tells n-1 helper threads to spin wait on work to do (not recommended).
JSON messages for all work types is new in version 29.6. You can turn off JSON
messages with this prime.txt option:
OutputJSON=0 or 1 (default is 1)
Setting OutputJSON=0 will stop prime95 from outputting JSON messages to results.json.txt.
When looking for probable primes, the following 3 options are available in prime.txt:
SilentVictoryPRP=0 or 1 (default is 1)
OutputPrimes=0 or 1 (default is 0)
OutputComposites=0 or 1 (default is 0)
Setting SilentVictoryPRP=0 will cause prime95 to make a continuous noise if a
non-Mersenne PRP is found (SilentVictory=0 or 1 applies to both Mersenne LL and PRP).
Setting OutputPrimes=1 will cause prime95 to output non-JSON messages for probable primes to results.txt.
Setting OutputComposites=1 will cause prime95 to output non-JSON messages for composite PRP tests to results.txt.
When PRPing k*b^n+c, there are two types of highly-reliable error checking available.
Gerbicz error checking is available when b=2 and there are either no known factors or
residue type (see following paragraphs) is 5. It almost guarantees a correct result
at an overhead of about 0.2%. The second high-reliability error check is to run the
PRP twice comparing residues along the way. Obviously, this doubles the runtime.
To select which error checking is performed or to disable error-checking, use the
following setting in prime.txt:
PRPErrorChecking=0 or 1 or 2 or 3 (default is 1)
Set to zero to disable high-reliability error checking. Set to 1 to perform Gerbicz
high-reliability error checking whenever possible, otherwise no error checking. Set
to 2 to do Gerbicz high-reliability error checking whenever possible, otherwise do the
much slower error check of doing each iteration twice and periodically comparing residues.
Set to 3 to force the much slower error check of doing each iteration twice and periodically
comparing residues.
When doing highly-reliable error checking, the interval between compares can be
controlled with these two settings in prime.txt:
PRPGerbiczCompareInterval=n (default is 1000000)
PRPDoublecheckCompareInterval=n (default is 100000)
Reducing the interval will reduce how far the program "rolls back" when an error
is detected. It will also increase the overhead associated with error-checking.
NOTE: For technical reasons, PRPGerbiczCompareInterval is rounded to the nearest perfect square.
ALSO NOTE: The program automatically adjusts the Gerbicz interval downward when an error is
detected. This will reduce the amount of time "lost" rolling back to the last verified good
iteration after an error is detected. Over time, the Gerbicz interval will be adjusted back
upward after many successful compares.
You can change the default base used in PRP tests. In prime.txt:
PRPBase=n (default 3)
The base can also be changed for individual PRP tests in worktodo.txt entries making
this option obsolete.
PRP supports 5 types of residues for compatibility with other PRP programs. If
a is the PRP base and N is the number being tested, then the residue types are:
1 = 64-bit residue of a^(N-1), a traditional Fermat PRP test used by most other programs
2 = 64-bit residue of a^((N-1)/2)
3 = 64-bit residue of a^(N+1), only available if b=2
4 = 64-bit residue of a^((N+1)/2), only available if b=2
5 = 64-bit residue of a^(N*known_factors-1), same as type 1 if there are no known factors
To control which residue type is generated, use this setting in prime.txt:
PRPResidueType=n (default is 5)
The residue type can also be set for PRP tests in worktodo.txt entries making
this option somewhat obsolete.
When PRPing k*b^n+c and b=2, there are some optimizations possible that reduce the
number of small constant multiplications. Although there should be no reason to turn
off these optimizations, it can be done with this setting in prime.txt:
PRPStraightForward=1 (default is 0)
Change this setting only when no PRP tests are in progress. Changing this setting
will invalidate existing save files.
NOTE: Selecting the straight forward (no optimization) code path disables the very
efficient and powerful Gerbicz error checking.
WINDOWS ONLY: You can have prime95 pause when the battery level gets low.
This will allow you to charge the battery faster. Add the line
BatteryPercent=n
to prime.txt, where n is a number from 0 to 100. The default value is zero.
LINUX/FREEBSD/APPLE ONLY: In prime.txt you can have set the nice level. By
default, on startup mprime automatically sets the program to nice priority.
This isn't really necessary since workers are usually set to run at a much
lower priority. However, sysadmins might be alarmed to see a CPU intensive
program not running at nice priority when they execute a ps command (it takes
a more complicated ps command to see that the CPU intensive threads are running
at a lower priority). You can change the nice level in prime.txt with the line:
Nice=n
where n is the nice level. The default nice level is 10. In Linux you can select
a value from -20 to +19. In FreeBSD and Mac OS X you can select a value
between -20 and 20. Higher numbers represent a "nicer" program (lower priority).
In all OSes, a zero nice level means run at the normal priority.