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Date: Fri, 1 Jul 2011 16:10:37 +0800 From: "Ma, Ling" <ling.ma@...el.com> To: "Ma, Ling" <ling.ma@...el.com>, Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org> CC: "hpa@...or.com" <hpa@...or.com>, "tglx@...utronix.de" <tglx@...utronix.de>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: RE: [PATCH RFC] [x86] Optimize copy-page by reducing impact from HW prefetch Forget to append experiment data: 1. We copy 4096 bytes for 32 times on snb, and extract minimum execution time On hot cache case: Copy_page copy_page_c 482 cycles 350 cycles 2. the same routine with hot-caches, but before each execution we copy 512k data to push original data out of L1 &L2. On cold cache case: copy_page(with prefetch) copy_page(without prefetch) copy_page_c 853~873 cycles 1037~1051 cycles 959~976 cycles Thanks Ling > -----Original Message----- > From: Ma, Ling > Sent: Tuesday, June 28, 2011 11:24 PM > To: 'Ingo Molnar'; Andi Kleen > Cc: hpa@...or.com; tglx@...utronix.de; linux-kernel@...r.kernel.org > Subject: RE: [PATCH RFC] [x86] Optimize copy-page by reducing impact > from HW prefetch > > Hi Ingo > > > 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? > Copy_page_c > on hot-cache copy_page_c on SNB combines data to 128bit (processor > limit 128bit/cycle for write) after startup latency > so it is faster than copy_page which provides 64bit/cycle for write. > > on cold-cache copy_page_c doesn't use prefetch, which uses prfetch > according to copy size, > so copy_page function is better. > > Thanks > Ling -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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