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[Bug string/19928] New: memmove-vec-unaligned-erms.S is slow with large data size
- From: "hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Fri, 08 Apr 2016 13:45:44 +0000
- Subject: [Bug string/19928] New: memmove-vec-unaligned-erms.S is slow with large data size
- Auto-submitted: auto-generated
https://sourceware.org/bugzilla/show_bug.cgi?id=19928
Bug ID: 19928
Summary: memmove-vec-unaligned-erms.S is slow with large data
size
Product: glibc
Version: 2.24
Status: NEW
Severity: normal
Priority: P2
Component: string
Assignee: unassigned at sourceware dot org
Reporter: hjl.tools at gmail dot com
Target Milestone: ---
Target: x86-64
Created attachment 9171
--> https://sourceware.org/bugzilla/attachment.cgi?id=9171&action=edit
bench-memcpy data on Intel Haswell machine with large data size
The large memcpy micro benchmark in glibc shows that there is a regression
with large data on Haswell. memmove-vec-unaligned-erms.S doesn't use
non-temporal store with large data size. Benchmark data shows that the
threshold to use non temporal store is approximately 6 times of shared cache
size. But non temporal store isn't a win on large data size when there is
overlap between destination and source since destination may be in cache
when source is loaded.
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