mtsieve

[rogue]

Originally Posted by ryanp

I've tried a number of combinations of -G and -g, ranging from "-g 16" up to "-G 8 -g 288". No matter what, it always tops out around 9.7 or 9.8M p/sec.

This is pretty surprising (the A100 has a max 19.5 TFlop/s single precision) considering I can easily get higher than that with 48 workers on a Xeon.

I have used -g500 (no -G). It is unlikely that the GPU is the bottleneck.

[ryanp]

Originally Posted by rogue

I have used -g500 (no -G). It is unlikely that the GPU is the bottleneck.

I've tested "-g 72", "-g 144", "-g 600" and for fun, "-g 6192". All produce about 7.5M to 8M p/sec.

With "-G 2" or "-G 4" added in as well, i can get up to about 9.5 to 9.8M p/sec, but no higher.

[R. Gerbicz]

Originally Posted by ryanp

On a Tesla A100, I couldn't get srsieve2cl to go much above 9 to 10M p/sec, after fiddling with values for a while. By comparison, a plain ./srsieve2 -W 48 on a 72-core Xeon CPU gives me about 15M p/sec.

Just for curiosity that is is how many k/n pairs, so what is the #k * (nmax-nmin) ?

[Citrix]

Originally Posted by rogue

I have used -g500 (no -G). It is unlikely that the GPU is the bottleneck.

The "Sieve of Eratosthenes" code becomes a bottle neck around 10-15 Mp/sec.

[henryzz]

Have you tried multiple instances of mtsieve?

[rogue]

Originally Posted by Citrix

The "Sieve of Eratosthenes" code becomes a bottle neck around 10-15 Mp/sec.

I use primesieve as the prime generator. Maybe it could be used in a more efficient manner.

[Citrix]

Originally Posted by rogue

I use primesieve as the prime generator. Maybe it could be used in a more efficient manner.

The license prevents us from changing the code. You could write a faster Sieve of Eratosthenes if you let a few composites slip through.

Originally Posted by henryzz

Have you tried multiple instances of mtsieve?

You can get 60MP/sec for 4 cores.

[Happy5214]

Would it be possible for mtsieve to return with a non-zero exit code if it was terminated manually (i.e. with SIGINT)? I have several shell scripts for the older srsieve family of programs that have that behavior, and it's useful to know whether the range completed (particularly when it comes to determining whether or not to update a sieve progress control file, which I currently have to revert manually to the old value if I manually kill an mtsieve-family sieve program).

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Originally Posted by Citrix

The license prevents us from changing the code. You could write a faster Sieve of Eratosthenes if you let a few composites slip through.

Assuming https://github.com/kimwalisch/primesieve is the same library, what stops you from forking it and modifying it? It's under a 2-clause BSD license, one of the most liberal FOSS licenses there is.

[rogue]

Originally Posted by Happy5214

Would it be possible for mtsieve to return with a non-zero exit code if it was terminated manually (i.e. with SIGINT)? I have several shell scripts for the older srsieve family of programs that have that behavior, and it's useful to know whether the range completed (particularly when it comes to determining whether or not to update a sieve progress control file, which I currently have to revert manually to the old value if I manually kill an mtsieve-family sieve program).

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Assuming https://github.com/kimwalisch/primesieve is the same library, what stops you from forking it and modifying it? It's under a 2-clause BSD license, one of the most liberal FOSS licenses there is.

The output when abnormally terminated has the string "Interrupted" in the text, e.g. "2021-10-01 13:16:49: Sieve interrupted at p=26666330822323". Can you parse the output to determine that it was stopped without completing the range?

The challenge is that the framework was designed around slower sieves, ones where each chunk of work takes much more time to process than getting the "chunk of work". This applies to most sieves. It doesn't work as well for faster sieves or computers with many/many cores where one wants a worker per core.

A "chunk of work" means a fixed number of primes, not a fixed range of primes. With the former, there is a mutex around the code getting the primes so that no two workers work on the same primes and so that each worker has the optimal number of primes for its looping logic.

I could change this to a "fixed range of primes". This is slightly less efficient for the worker threads, but significantly reduces the scope of the mutex.

[Citrix]

Originally Posted by Happy5214

Assuming https://github.com/kimwalisch/primesieve is the same library, what stops you from forking it and modifying it? It's under a 2-clause BSD license, one of the most liberal FOSS licenses there is.

It was under a different license before.
Maybe this would be helpful:-
https://github.com/curtisseizert/CUDASieve

[matzetoni]

> gfndsievecl.exe -n22001 -N25000 -k2000000 -K3000000 -o"out1.txt"

I tried running above input with the newest mtsieve version 2.2.2.7 and the program just exits after 5 minutes with no output / error in log file written.