July 2016 - Intel-nda - mailman3.cels.anl.gov

Re: [JLSE-Intel-NDA] disable HW prefetch on KNL
by Kumbhar Pramod Shivaji 06 Jul '16

06 Jul '16

Regarding knl hardware prefetcher, I read something like “hardware prefetchers can be disabled within the BIOS menus at boot time or using BIOS tools, specific to your machine”. I am not sure if this is true (for current knl nodes / BIOS), people who can look at BIOS settings or intel folks can provide more information regarding this. “software” or “compiler” prefetching is enabled by default with -O2 which could be disabled by -opt-prefetch=0 / -no-opt-prefetch or “pragma noprefetch”. I see prefetch instructions like prefetcht0, prefetchnt1 or _mm_prefetch intrinsics but haven’t come across anything to disable it like data stream control register you mentioned for power8 (expect for some<https://software.intel.com/en-us/articles/disclosure-of-hw-prefetcher-contr…> other microarchitectures). -Pramod On 06 Jul 2016, at 08:29, Delalondre Fabien Jonathan <fabien.delalondre(a)epfl.ch<mailto:[email protected]>> wrote: Last time i asked intel it was not possible to disable hardware prefetcher. I believe you can pass hints to indicate you want to disable software prefetcher but i dont remember whether they were just hints (that can be ignored) or not. Best, Fabien On 6 juil. 2016, at 00:05, Chunduri, Sudheer <chunduri(a)anl.gov<mailto:[email protected]>> wrote: Hi, Is there a way to disable HW prefetch on KNL? For ex, on POWER8, user can use intrinsics such as __prefetch_set_dscr_register(40) to disable hw prefetch Or user can use a compiler flag to control prefetch. Is there a similar method available for KNL? regards Sudheer _______________________________________________ Intel-nda mailing list Intel-nda(a)lists.jlse.anl.gov<mailto:[email protected]> https://lists.jlse.anl.gov/mailman/listinfo/intel-nda _______________________________________________ Intel-nda mailing list Intel-nda(a)lists.jlse.anl.gov<mailto:[email protected]> https://lists.jlse.anl.gov/mailman/listinfo/intel-nda

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[JLSE-Intel-NDA] Checking BIOS settings on knl nodes (sudo access)
by Kumbhar Pramod Shivaji 06 Jul '16

06 Jul '16

Hello, I would like to see the BIOS settings on knl nodes using below command: sudo /usr/bin/syscfg/syscfg /s settings.txt This requires sudo access. Would it be possible to get above settings information? I assume sudo access is limited and wondering if it would be possible to get sudo permissions to check above settings. Thank you! -Pramod

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Re: [JLSE-Intel-NDA] disable HW prefetch on KNL
by Delalondre Fabien Jonathan 06 Jul '16

06 Jul '16

Last time i asked intel it was not possible to disable hardware prefetcher. I believe you can pass hints to indicate you want to disable software prefetcher but i dont remember whether they were just hints (that can be ignored) or not. Best, Fabien On 6 juil. 2016, at 00:05, Chunduri, Sudheer <chunduri(a)anl.gov<mailto:[email protected]>> wrote: Hi, Is there a way to disable HW prefetch on KNL? For ex, on POWER8, user can use intrinsics such as __prefetch_set_dscr_register(40) to disable hw prefetch Or user can use a compiler flag to control prefetch. Is there a similar method available for KNL? regards Sudheer _______________________________________________ Intel-nda mailing list Intel-nda(a)lists.jlse.anl.gov<mailto:[email protected]> https://lists.jlse.anl.gov/mailman/listinfo/intel-nda

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[JLSE-Intel-NDA] disable HW prefetch on KNL
by Chunduri, Sudheer 05 Jul '16

05 Jul '16

Hi, Is there a way to disable HW prefetch on KNL? For ex, on POWER8, user can use intrinsics such as __prefetch_set_dscr_register(40) to disable hw prefetch Or user can use a compiler flag to control prefetch. Is there a similar method available for KNL? regards Sudheer

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