On Thu, 16 Mar 2017 01:50:39 +0100 Victor Stinner <victor.stinner@gmail.com> wrote:
I made my own experiment on the impact on temperature on performance, and above 100°C, I didn't notice anything: https://haypo.github.io/intel-cpus-part2.html "Impact of the CPU temperature on benchmarks"
I suspect temperature can have an impact on performance if Turbo is enabled (or, as you noticed, if CPU cooling is deficient).
Note that tweaking a system for benchmarking (disabling Turbo, disabling ASLR, etc.) may make the results more reproducible, but it may also make them less representative of real-world conditions (because few people disable Turbo or ASLR, except precisely on benchmarking machines :-)). It's a delicate balancing act!
Regards
Antoine.
2017-03-16 10:22 GMT+01:00 Antoine Pitrou <solipsis@pitrou.net>:
I suspect temperature can have an impact on performance if Turbo is enabled (or, as you noticed, if CPU cooling is deficient).
Oh sure, I now always start by disabling Turbo Boost. It's common that I run benchmarks on my desktop PC with Firefox running in the background. Variable workload on other CPUs is very likely to change the peak CPU frequency on the CPUs used for benhcmarks, even if CPU isolation and CPU pinning is used.
Note that tweaking a system for benchmarking (disabling Turbo, disabling ASLR, etc.) may make the results more reproducible, but it may also make them less representative of real-world conditions (because few people disable Turbo or ASLR, except precisely on benchmarking machines :-)). It's a delicate balancing act!
Yeah, that's also why I chose to enable ASLR. I fear that disabling ASLR will put me a "local minimum" which is not representative of average performance when ASLR is enabled and benchmark run using multiple processes (to test multiple address layouts).
Victor
[Wang, Peter Xihong] I am wondering what others are using micro-benchmarks for, or if there is a usage statistics somewhere about these benchmarks. For me, it's optimization delta driven. e.g., if I expect my optimization to boost performance by 5%, but the variation reaches up to or greater than 5%, then I am getting lost, and the perf data cannot be trusted.
In addition to turbo boost, I also turned off hyperthreading, and c-state, p-state, on Intel CPUs.
Regards,
Peter
-----Original Message----- From: Speed [mailto:speed- bounces+peter.xihong.wang=intel.com@python.org] On Behalf Of Antoine Pitrou Sent: Thursday, March 16, 2017 2:22 AM To: speed@python.org Subject: Re: [Speed] ASLR
On Thu, 16 Mar 2017 01:50:39 +0100 Victor Stinner <victor.stinner@gmail.com> wrote:
I made my own experiment on the impact on temperature on performance, and above 100°C, I didn't notice anything: https://haypo.github.io/intel-cpus-part2.html "Impact of the CPU temperature on benchmarks"
I suspect temperature can have an impact on performance if Turbo is enabled (or, as you noticed, if CPU cooling is deficient).
Note that tweaking a system for benchmarking (disabling Turbo, disabling ASLR, etc.) may make the results more reproducible, but it may also make them less representative of real-world conditions (because few people disable Turbo or ASLR, except precisely on benchmarking machines :-)). It's a delicate balancing act!
Regards
Antoine.
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participants (3)
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Antoine Pitrou -
Victor Stinner -
Wang, Peter Xihong