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authorChen, Kenneth W <kenneth.w.chen@intel.com>2006-03-22 00:09:03 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-22 07:54:04 -0800
commitd5d4b0aa4e1430d73050babba999365593bdb9d2 (patch)
tree67199d156f61217f9493d31aa4a9bfbb9c97412e /mm/vmscan.c
parentbba1e9b2111b14625f670bd07e57fd7ed57ce804 (diff)
[PATCH] optimize follow_hugetlb_page
follow_hugetlb_page() walks a range of user virtual address and then fills in list of struct page * into an array that is passed from the argument list. It also gets a reference count via get_page(). For compound page, get_page() actually traverse back to head page via page_private() macro and then adds a reference count to the head page. Since we are doing a virt to pte look up, kernel already has a struct page pointer into the head page. So instead of traverse into the small unit page struct and then follow a link back to the head page, optimize that with incrementing the reference count directly on the head page. The benefit is that we don't take a cache miss on accessing page struct for the corresponding user address and more importantly, not to pollute the cache with a "not very useful" round trip of pointer chasing. This adds a moderate performance gain on an I/O intensive database transaction workload. Signed-off-by: Ken Chen <kenneth.w.chen@intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/vmscan.c')
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