On Thu, Nov 17, 2011 at 7:03 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> wrote: > > I'll send this again when mm is shipped. > I sometimes see mem_cgroup_split_huge_fixup() in perf report and noticed > it's very slow. This fixes it. Any comments are welcome. > How do you see this - what tests? > == > Subject: [PATCH] fix mem_cgroup_split_huge_fixup to work efficiently. > > at split_huge_page(), mem_cgroup_split_huge_fixup() is called to > handle page_cgroup modifcations. It takes move_lock_page_cgroup() > and modify page_cgroup and LRU accounting jobs and called > HPAGE_PMD_SIZE - 1 times. > > But thinking again, > - compound_lock() is held at move_accout...then, it's not necessary > to take move_lock_page_cgroup(). > - LRU is locked and all tail pages will go into the same LRU as > head is now on. > - page_cgroup is contiguous in huge page range. > > This patch fixes mem_cgroup_split_huge_fixup() as to be called once per > hugepage and reduce costs for spliting. The change seems reasonable, I am working on a test setup and hope to test it soon Balbir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href