Prime95 version 27.7 / 27.9

[Prime95]

Prime95 version 27.7 build 2 is available. My second attempt at a release candidate. If no major problems are reported this will become the official GIMPS client.

This version also fixes a few rare bugs in 27.6 (see http://mersenneforum.org/showpost.ph...58&postcount=2). It also fixes a bug partly responsible for the rare false positive reports GIMPS has seen in recent years. As part of this fix, a save file that cannot be read will be renamed with a .bad extension in hopes that the file can be successfully read at a later time (yes, this can happen).

Also, note the new naming scheme for downloads.

Download links:
Windows 64-bit: ftp://mersenne.org/gimps/p95v277.win64.zip
Windows 32-bit: ftp://mersenne.org/gimps/p95v277.win32.zip
Linux 64-bit: ftp://mersenne.org/gimps/p95v277.linux64.tar.gz
Linux 32-bit: ftp://mersenne.org/gimps/p95v277.linux32.tar.gz
Mac OS X: ftp://mersenne.org/gimps/p95v277.MacOSX.zip
FreeBSD 64-bit: ftp://mersenne.org/gimps/p95v277.FreeBSD64.tar.gz
Source code: ftp://mersenne.org/gimps/p95v277.source.zip
Windows 64-bit service: ftp://mersenne.org/gimps/p95v277.win64.service.zip
Windows 32-bit service: ftp://mersenne.org/gimps/p95v277.win32.service.zip

[Prime95]

1. SoB cannot package a default prime.txt with the Mac OS X version because the Mac version changes the working directory to ~/Prime95. Mac version changed to copy a prime.txt file from the application bundle to ~/Prime95. Fixed in version 27.7 build 2.
2. Root cause of several false prime reports in recent years found. Fixed in version 27.7 build 2.
3. AffinityScramble has a bug when more than 36 cores are present. Fixed in version 27.7 build 3.
4. Modern Linux seems to use /sys/class/power_supply/ instead of /proc/acpi/battery/. Both will be supported in 27.7 build 3.
5. Adding FFT2=32M to worktodo.ini lines does not work for exponents above 595,800,000. Fixed in 27.7 build 4.
6. Small one-pass AVX FFTs have a data-dependent bug that can cause an infinite loop -- most likely to occur in the very smallest FFT sizes. Fixed in 27.8.
7. Using more than 16 threads in an SSE2 8K FFT caused a crash. Fixed in 27.9.
8. Mac OS X version crashes when merging worker window's output. Fixed in 27.9.
9. Prime95 may get roundoff errors testing numbers with a large base such as PRP of 2*25735^25735-1. In 27.9, prime95 will be somewhat less aggressive in choosing FFT sizes when the base is above 5800.
10. Multi-threaded FFTs sometimes get spurious very large roundoff errors. Fixed in 27.9.
11. On some systems (depends on the implementation of strcpy) the GMPECMHook=1 option will output incorrect values. Fixed in 27.10.
12. On some systems (depends on the implementation of memcpy) the GCD code could return an incorrect value. Fortunately, only Alex Kruppa seems to get this error and the last error. Fixed in 27.10.
13. Small one-pass AVX FFTs have a data-dependent bug in the carry propagation code. This bug mainly affects length 32 FFTs, but could affect FFTs up to length 256. Fixed in 27.11.
14. If P-1 stage 1 backtracks due to an excessive roundoff error then there is a 50% chance the P-1 result will be corrupted. Fixed in 28.2.
15. PRP of the number one (can accidentally occur as in PRP=1,2,101,-1,"7432339208719,341117531003194129") crashed. Fixed in Windows 28.3 and Linux 28.4.

[Xyzzy]

http://www.mersenneforum.org/gimps/

[Chuck]

Originally Posted by Prime95

<placeholder for known bugs and fixes>

[May 4 08:03] Waiting 10 seconds to stagger worker starts.
[May 4 08:03] Worker starting
[May 4 08:03] Setting affinity to run worker on any logical CPU.
[May 4 08:03] Optimal P-1 factoring of M56320727 using up to 8000MB of memory.
[May 4 08:03] Assuming no factors below 2^72 and 2 primality tests saved if a factor is found.
[May 4 08:03] Optimal bounds are B1=565000, B2=12147500
[May 4 08:03] Chance of finding a factor is an estimated 4.2%
[May 4 08:03] Using FFT length 3M, Pass1=768, Pass2=4K
[May 4 08:03] Available memory is 7938MB.
[May 4 08:03] Using 7391MB of memory.  Processing 288 relative primes (0 of 288 already processed).
[May 4 08:07] Memory allocation error.  Trying again using less memory.
[May 4 08:07] Using FFT length 3M, Pass1=768, Pass2=4K
[May 4 08:07] Available memory is 6350MB.
[May 4 08:07] Using 6344MB of memory.  Processing 245 relative primes (0 of 288 already processed).
[May 4 08:11] Memory allocation error.  Trying again using less memory.
[May 4 08:11] Using FFT length 3M, Pass1=768, Pass2=4K
[May 4 08:11] Available memory is 5080MB.
[May 4 08:11] Using 5077MB of memory.  Processing 193 relative primes (0 of 288 already processed).

I started getting this memory error as soon as I installed the new 27.1 version. I have not had a memory error on this computer since it was new 1 1/2 years ago.

I fell back to 27.6 build 3 and the problem went away. Using Windows 7 64 bit with Core-i7 970 12 Mb memory

Chuck

[BrianOC]

27.7 good small FTT no error.

[Prime95]

Originally Posted by Chuck

I fell back to 27.6 build 3 and the problem went away. Using Windows 7 64 bit with Core-i7 970 12 Mb memory

There is no difference between 27.6 and 27.7 with respect to allocating P-1 memory.

[Chuck]

Originally Posted by Prime95

There is no difference between 27.6 and 27.7 with respect to allocating P-1 memory.

Nuts — my error — I went to Xyzzy's mirror site to get the software and mistakenly picked up the 32 bit version instead of the 64 bit. Sorry for the false report.

Chuck

[flashjh]

Originally Posted by Chuck

Nuts — my error — I went to Xyzzy's mirror site to get the software and mistakenly picked up the 32 bit version instead of the 64 bit. Sorry for the false report.

Chuck

At least it's not your RAM ;)

[kladner]

Originally Posted by Chuck

.....mistakenly picked up the 32 bit version instead of the 64 bit.....

Chuck

Been there. Done that.

[henryzz]

Originally Posted by Chuck

Nuts — my error — I went to Xyzzy's mirror site to get the software and mistakenly picked up the 32 bit version instead of the 64 bit. Sorry for the false report.

Chuck

Maybe there should be a warning that 32-bit is the problem.

[Chuck]

Originally Posted by henryzz

Maybe there should be a warning that 32-bit is the problem.

No I just shouldn't be STUPID and not paying attention.