From: Eric Dumazet Date: Sat, 10 Feb 2007 09:44:48 +0000 (-0800) Subject: [PATCH] struct vfsmount: keep mnt_count & mnt_expiry_mark away from mnt_flags X-Git-Tag: v2.6.21-rc1~274^2~370 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ba4d4c0c52201009232fe9e781a281054a24e75;p=pandora-kernel.git [PATCH] struct vfsmount: keep mnt_count & mnt_expiry_mark away from mnt_flags I noticed cache misses in touch_atime() that can be avoided if we keep mnt_count & mnt_expiry_mark in a different cache line than mnt_flags (mostly read) mnt_count & mnt_expiry_mark are modified each time a file is opened/closed in a file system. touch_atime() is called each time a file is read, and generally needs to read mnt_flags. Other fields of struct vfsmount are mostly read so I chose to move mnt_count & mnt_expiry_mark at the end of struct vfsmount. And adding a comment so that nobody tries to re-arrange fields to fill the holes :) On 64bits platforms, the new offsetof(mnt_count) is 0xC0 On 32bits platforms, it is 0x60, so I didnot add a ____cacheline_aligned_in_smp because it would have a too big impact on the size of this object (in particular if CONFIG_X86_L1_CACHE_SHIFT=7) Signed-off-by: Eric Dumazet Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed