Messages in this thread |  | | | Date | Mon, 21 Nov 2011 16:30:11 +0530 | | Subject | Re: [PATCH] fix mem_cgroup_split_huge_fixup to work efficiently. | | From | Balbir Singh <> |
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On Thu, Nov 17, 2011 at 7:03 AM, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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