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Groups > linux.kernel > #1464328
| From | Borislav Petkov <bp@suse.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement |
| Date | 2016-08-17 07:50 +0200 |
| Message-ID | <s71TH-5aR-1@gated-at.bofh.it> (permalink) |
| References | <s6Nxo-4cZ-11@gated-at.bofh.it> <s6PSx-5xO-1@gated-at.bofh.it> <s6QbU-5V1-33@gated-at.bofh.it> <s6VOh-161-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Tue, Aug 16, 2016 at 04:09:19PM -0700, H. Peter Anvin wrote:
> On August 16, 2016 10:16:35 AM PDT, Borislav Petkov <bp@suse.de> wrote:
> >On Tue, Aug 16, 2016 at 09:59:00AM -0700, H. Peter Anvin wrote:
> >> Dang...
> >
> >Isn't 9.3% improvement a good thing(tm) ?
>
> Yes, it's huge. The only explanation I could imagine is that scrambling %rdi caused the scheduler to do completely the wrong thing.
I'm questioning the validity, actually. Report says test machine was
Sandy Bridge-EP and I'd bet good money this one has POPCNT support so
how are we even hitting that __sw_hweight64() path, at all?
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
--
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Re: [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement "H. Peter Anvin" <hpa@zytor.com> - 2016-08-16 19:00 +0200
Re: [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement Borislav Petkov <bp@suse.de> - 2016-08-16 19:20 +0200
Re: [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement "H. Peter Anvin" <hpa@zytor.com> - 2016-08-17 01:20 +0200
Re: [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement Borislav Petkov <bp@suse.de> - 2016-08-17 07:50 +0200
Re: [LKP] [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement "Huang\, Ying" <ying.huang@intel.com> - 2016-08-18 00:30 +0200
Re: [LKP] [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement Borislav Petkov <bp@suse.de> - 2016-08-18 05:50 +0200
Re: [LKP] [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement "Huang\, Ying" <ying.huang@intel.com> - 2016-08-18 06:00 +0200
Re: [LKP] [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement Borislav Petkov <bp@suse.de> - 2016-08-18 06:20 +0200
Re: [LKP] [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement "H. Peter Anvin" <hpa@zytor.com> - 2016-08-18 06:00 +0200
Re: [lkp] [x86/hweight] 65ea11ec6a: will-it-scale.per_process_ops 9.3% improvement Peter Zijlstra <peterz@infradead.org> - 2016-08-17 08:50 +0200
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