Messages in this thread | | | From | "Ma, Ling" <> | Date | Fri, 24 Jun 2011 10:01:28 +0800 | Subject | RE: [PATCH RFC] [x86] Optimize copy-page by reducing impact from HW prefetch |
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Sure, I separate two patches ASAP, one is for performance tuning code after some experiments, another code style patch.
Thanks Ling
> -----Original Message----- > From: Ingo Molnar [mailto:mingo@elte.hu] > Sent: Thursday, June 23, 2011 3:05 PM > To: Andi Kleen > Cc: Ma, Ling; hpa@zytor.com; tglx@linutronix.de; linux- > kernel@vger.kernel.org > Subject: Re: [PATCH RFC] [x86] Optimize copy-page by reducing impact > from HW prefetch > > > * Andi Kleen <andi@firstfloor.org> wrote: > > > ling.ma@intel.com writes: > > > > > impact(DCU prefetcher), and simplify original code. The > > > performance is improved about 15% on core2, 36% on snb > > > respectively. (We use our micro-benchmark, and will do further > > > test according to your requirment) > > > > This doesn't make a lot of sense because neither Core-2 nor SNB use > > the code path you patched. They all use the rep ; movs path > > Ling, mind double checking which one is the faster/better one on SNB, > in cold-cache and hot-cache situations, copy_page or copy_page_c? > > Also, while looking at this file please fix the countless pieces of > style excrements it has before modifying it: > > - non-Linux comment style (and needless two comments - it can > be in one comment block): > > /* Don't use streaming store because it's better when the target > ends up in cache. */ > > /* Could vary the prefetch distance based on SMP/UP */ > > - (there's other non-standard comment blocks in this file as well) > > - The copy_page/copy_page_c naming is needlessly obfuscated, it > should be copy_page, copy_page_norep or so - the _c postfix has no > obvious meaning. > > - all #include's should be at the top > > - please standardize it on the 'instrn %x, %y' pattern that we > generally use in arch/x86/, not 'instrn %x,%y' pattern. > > and do this cleanup patch first and the speedup on top of it, and > keep the two in two separate patches so that the modification to the > assembly code can be reviewed more easily. > > Thanks, > > Ingo
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