Date: Tue, 13 Apr 2010 08:24:35 +0900 (JST) From: Maho NAKATA <chat95@mac.com> To: lists@mawer.org Cc: adrian@freebsd.org, freebsd-stable@freebsd.org Subject: Re: Only 70% of theoretical peak performance on FreeBSD 8/amd64, Corei7 920 Message-ID: <20100413.082435.787670930925495306.chat95@mac.com> In-Reply-To: <h2yea2d4a5b1004120658xba353f17w894d33e08558f3ea@mail.gmail.com> References: <20100412.131213.4959786962516027.chat95@mac.com> <t2ud763ac661004120231q44e9a4f7z5c0f11a31725deb@mail.gmail.com> <h2yea2d4a5b1004120658xba353f17w894d33e08558f3ea@mail.gmail.com>
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Hi Antony I think this is not the case. I tested TurboBoost on/off on Ubuntu, Got= oBLAS achieved 95% of theoretical perfomance for both cases. cf. http://www.intel.com/support/processors/sb/cs-023143.htm and http://blog.goo.ne.jp/nakatamaho/e/86c0f4ac529fd5b530454ed795e6b466= (written in Japanese, tho) Thanks From: Antony Mawer <lists@mawer.org> Subject: Re: Only 70% of theoretical peak performance on FreeBSD 8/amd6= 4, Corei7 920 Date: Mon, 12 Apr 2010 23:58:17 +1000 > This may well be the same sort of issue that was discussed in this th= read here: > = > http://lists.freebsd.org/pipermail/freebsd-hackers/2010-March/031= 004.html > = > In short, the Core i7 CPUs have a feature called "TurboBoost" where > the clock speed of one or more cores is boosted when other cores are > idle and in a C2 or C3 sleep status ... if the appropriate power > saving mode isn't active on the system (which I don't think FreeBSD > does by default?), the idle cores are never put into the appropriate > power saving state, and as a result TurboBoost never kicks in... > = > It _may_ be that Ubuntu configures this correctly whereas FreeBSD doe= s > not (out of the box)? > = > Of course it may be something else entirely, but worth checking out..= .= > = > --Antony > = > On Mon, Apr 12, 2010 at 7:31 PM, Adrian Chadd <adrian@freebsd.org> wr= ote: >> Of course, what would be helpful is actually figuring out what is >> going on rather than some conjecture. :) >> >> With what he said, tweaking memory allocation under FreeBSD and/or >> linux would change the performance characteristics and either valida= te >> or disprove his assumptions? >> >> >> Adrian >> >> On 12 April 2010 12:12, Maho NAKATA <chat95@mac.com> wrote: >>> Hi FreeBSD developers, >>> [the original article in Japanese can be found at >>> http://blog.goo.ne.jp/nakatamaho/e/b5f6fbc3cc6e1ac4947463eb1ca4eb0a= ] >>> >>> *Abstract* >>> I compared the peak performance of FreeBSD 8.0/amd64 and Ubuntu 9.1= 0 amd64 using dgemm >>> (a linear algebra routine, matrix-matrix multiplication). >>> I obtained only 70% of theoretical peak performance on FreeBSD 8/am= d64 and >>> almost 95% on Ubuntu 9.10 /amd64. I'm really disappointed. >>> >>> *Introduction* >>> I'm a friend of Gotoh Kazushige, the principal developers of GotoBL= AS. He told me that >>> FreeBSD is not suitable OS for scientific computing or high perform= ance computing. He says >>> (in Japanese and my translation): >>> >>>> I guess FreeBSD does page coloring, but I don't think FreeBSD cons= iders very large cache >>>> size which recent CPU has. Support of a very large cache on Linux = is still not very will >>>> sophisticated, but on *BSDs, its worst; they uses too fine memory = allocation method, >>>> so we cannot expect large continuous physical memory allocation. >>>> Moreover, process scheduling is not so nice as *BSD employs an alg= orithm that >>>> changes physical CPUs in turn instead of allocating one core for s= uch kind of jobs. >>>> Take your own benchmark, and you'll see.. >>> >>> *Result* >>> Machine: Core i7 920 (42.56-44.8Gflops) / DDR3 1066 >>> OS: FreeBSD 8.0/amd64 and Ubuntu 9.10 >>> GotoBLAS2: 1.13 >>> >>> dgemm result >>> OS =A0 =A0 =A0: FLOPS =A0 =A0 =A0 =A0 =A0 : percent in peak >>> FreeBSD : 32.0 GFlops =A0 =A0 : 71% >>> Ubuntu =A0: 42.0-42.7GFlops : 93.8%-95.3% >>> >>> Thanks, >>> -- Nakata Maho http://accc.riken.jp/maho/ , http://ja.openoffice.or= g/ >>> =A0 Nakata Maho's PGP public keys: http://accc.riken.jp/maho/maho.p= gp.txt >>> >>> >>> >>> >>> _______________________________________________ >>> freebsd-stable@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-stable >>> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebs= d.org" >>> >> _______________________________________________ >> freebsd-stable@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-stable >> To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd= .org" >> > _______________________________________________ > freebsd-stable@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.= org" > =
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