Messages in this thread | | | Date | Thu, 24 May 2012 21:50:19 -0400 (EDT) | Subject | Re: [PATCH] x86/copy_user_generic: Optimize copy_user_generic with CPU erms feature | From | David Miller <> |
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From: "Fenghua Yu" <fenghua.yu@intel.com> Date: Thu, 24 May 2012 18:19:45 -0700
> According to Intel 64 and IA-32 SDM and Optimization Reference > Manual, beginning with Ivybridge, REG string operation using MOVSB > and STOSB can provide both flexible and high-performance REG string > operations in cases like memory copy. Enhancement availability is > indicated by CPUID.7.0.EBX[9] (Enhanced REP MOVSB/ STOSB).
How does the cpu do overlap detection?
If the cpu does overlap detection on sub-pagesize bits, performance will unnecessarily suffer under such circumstances.
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