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authorEric Dumazet <dada1@cosmosbay.com>2008-02-06 12:37:56 +0300
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-06 21:41:09 +0300
commit1bf47346d75790ebd2563d909d48046961c7ffd5 (patch)
tree0f478764beb8dc4e0c71c5f3d6a657535579fe3a /lib/smp_processor_id.c
parent6b2fb3c65844452bb9e8b449d50863d1b36c5dc0 (diff)
downloadlinux-1bf47346d75790ebd2563d909d48046961c7ffd5.tar.xz
kernel/sys.c: get rid of expensive divides in groups_sort()
groups_sort() can be quite long if user loads a large gid table. This is because GROUP_AT(group_info, some_integer) uses an integer divide. So having to do XXX thousand divides during one syscall can lead to very high latencies. (NGROUPS_MAX=65536) In the past (25 Mar 2006), an analog problem was found in groups_search() (commit d74beb9f33a5f16d2965f11b275e401f225c949d ) and at that time I changed some variables to unsigned int. I believe that a more generic fix is to make sure NGROUPS_PER_BLOCK is unsigned. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/smp_processor_id.c')
0 files changed, 0 insertions, 0 deletions