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authorBob Pearson <rpearson@systemfabricworks.com>2012-03-23 15:02:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-23 16:58:37 -0700
commit0292c497b6b942557d085b37f888ef5865f67d37 (patch)
treefe88508060c0ecdf8fb3d5e98ca2c55057cc5068 /firmware
parent324eb0f17d9dcead3c60c133aa244f6b3631fec9 (diff)
downloadop-kernel-dev-0292c497b6b942557d085b37f888ef5865f67d37.zip
op-kernel-dev-0292c497b6b942557d085b37f888ef5865f67d37.tar.gz
crc32: optimize loop counter for x86
Add two changes that improve the performance of x86 systems 1. replace main loop with incrementing counter this change improves the performance of the selftest by about 5-6% on Nehalem CPUs. The apparent reason is that the compiler can use the loop index to perform an indexed memory access. This is reported to make the performance of PowerPC CPUs to get worse. 2. replace the rem_len loop with incrementing counter this change improves the performance of the selftest, which has more than the usual number of occurances, by about 1-2% on x86 CPUs. In actual work loads the length is most often a multiple of 4 bytes and this code does not get executed as often if at all. Again this change is reported to make the performance of PowerPC get worse. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'firmware')
0 files changed, 0 insertions, 0 deletions
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