Re: OpenBSD performance upgrade
It uses AVX2, so... thanks for the extra seconds. :D Cheers. Elias. 2018-06-09 0:43 GMT-03:00 Philip Guenther : > On Fri, Jun 8, 2018 at 10:13 AM Elias M. Mariani > wrote: >> >> I usually run long computations on OpenBSD-current, in the last few >> days I see an upgrade in the performance of the process (in this case >> I have 6 threads running a very optimized assembler code). >> Each iteration of the code was about 14 sec. and now is around 13 sec. >> Don't mind the computation, the question is more about if something >> was changed (and if so what) to hit the performance so much, the >> compilation is the same as before, so the code did not change and the >> software does not use anything from ports, only the standard C >> library. >> >> A more accurate description would be that the threads are more >> homogeneous in relation with the iterations time, maybe one thread >> suddenly give a 11 sec. result, and another 15, probably related with >> thread reallocations, now I have a steady time in all the threads and >> in average the numbers are better. >> Anyways... Better is better. Just curious to know why is working better. >> :D > > > If the "optimized assembler" that the threads are running uses AVX or > similar "extended CPU state" extensions then the improvement is almost > certainly from my switch amd64 from "lazy FPU switching" to what I'll call > "semi-eager switching", where the current thread's registers are always > ensured to be loaded before returning to userspace, eliminating the need for > extra userspace->kernel->userspace transitions and IPIs to load the > registers in the current CPU. > > Glad to hear it's such a large improvement for your processing. Enjoy, and > remember to tip your OS vendor! > > > Philip Guenther >
Re: OpenBSD performance upgrade
On Fri, Jun 8, 2018 at 10:13 AM Elias M. Mariani wrote: > I usually run long computations on OpenBSD-current, in the last few > days I see an upgrade in the performance of the process (in this case > I have 6 threads running a very optimized assembler code). > Each iteration of the code was about 14 sec. and now is around 13 sec. > Don't mind the computation, the question is more about if something > was changed (and if so what) to hit the performance so much, the > compilation is the same as before, so the code did not change and the > software does not use anything from ports, only the standard C > library. > A more accurate description would be that the threads are more > homogeneous in relation with the iterations time, maybe one thread > suddenly give a 11 sec. result, and another 15, probably related with > thread reallocations, now I have a steady time in all the threads and > in average the numbers are better. > Anyways... Better is better. Just curious to know why is working better. :D > If the "optimized assembler" that the threads are running uses AVX or similar "extended CPU state" extensions then the improvement is almost certainly from my switch amd64 from "lazy FPU switching" to what I'll call "semi-eager switching", where the current thread's registers are always ensured to be loaded before returning to userspace, eliminating the need for extra userspace->kernel->userspace transitions and IPIs to load the registers in the current CPU. Glad to hear it's such a large improvement for your processing. Enjoy, and remember to tip your OS vendor! Philip Guenther
Re: OpenBSD performance upgrade
Forgot to add: amd64, last version of current. 2018-06-08 14:12 GMT-03:00 Elias M. Mariani : > Hi, > Just another silly question. > I usually run long computations on OpenBSD-current, in the last few > days I see an upgrade in the performance of the process (in this case > I have 6 threads running a very optimized assembler code). > Each iteration of the code was about 14 sec. and now is around 13 sec. > Don't mind the computation, the question is more about if something > was changed (and if so what) to hit the performance so much, the > compilation is the same as before, so the code did not change and the > software does not use anything from ports, only the standard C > library. > A more accurate description would be that the threads are more > homogeneous in relation with the iterations time, maybe one thread > suddenly give a 11 sec. result, and another 15, probably related with > thread reallocations, now I have a steady time in all the threads and > in average the numbers are better. > Anyways... Better is better. Just curious to know why is working better. :D > > Cheers. > Elias,
OpenBSD performance upgrade
Hi, Just another silly question. I usually run long computations on OpenBSD-current, in the last few days I see an upgrade in the performance of the process (in this case I have 6 threads running a very optimized assembler code). Each iteration of the code was about 14 sec. and now is around 13 sec. Don't mind the computation, the question is more about if something was changed (and if so what) to hit the performance so much, the compilation is the same as before, so the code did not change and the software does not use anything from ports, only the standard C library. A more accurate description would be that the threads are more homogeneous in relation with the iterations time, maybe one thread suddenly give a 11 sec. result, and another 15, probably related with thread reallocations, now I have a steady time in all the threads and in average the numbers are better. Anyways... Better is better. Just curious to know why is working better. :D Cheers. Elias,
