Messages in this thread | | | Date | Fri, 3 Jun 2011 07:23:48 +0900 | Subject | Re: [PATCH] mm: compaction: Abort compaction if too many pages are isolated and caller is asynchronous | From | Minchan Kim <> |
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Hi Andrea,
On Fri, Jun 3, 2011 at 6:40 AM, Andrea Arcangeli <aarcange@redhat.com> wrote: > Hello Minchan, > > On Fri, Jun 03, 2011 at 05:21:56AM +0900, Minchan Kim wrote: >> Isn't it rather aggressive? >> I think cursor page is likely to be PageTail rather than PageHead. >> Could we handle it simply with below code? > > It's not so likely, there is small percentage of compound pages that > aren't THP compared to the rest that is either regular pagecache or > anon regular or anon THP or regular shm. If it's THP chances are we
I mean we have more tail pages than head pages. So I think we are likely to meet tail pages. Of course, compared to all pages(page cache, anon and so on), compound pages would be very small percentage.
> isolated the head and it's useless to insist on more tail pages (at > least for large page size like on x86). Plus we've compaction so
I can't understand your point. Could you elaborate it?
> insisting and screwing lru ordering isn't worth it, better to be > permissive and abort... in fact I wouldn't dislike to remove the > entire lumpy logic when COMPACTION_BUILD is true, but that alters the > trace too...
AFAIK, it's final destination to go as compaction will not break lru ordering if my patch(inorder-putback) is merged.
> >> get_page(cursor_page) >> /* The page is freed already */ >> if (1 == page_count(cursor_page)) { >> put_page(cursor_page) >> continue; >> } >> put_page(cursor_page); > > We can't call get_page on an tail page or we break split_huge_page,
Why don't we call get_page on tail page if tail page isn't free? Maybe I need investigating split_huge_page.
> only an isolated lru can be boosted, if we take the lru_lock and we > check the page is in lru, then we can isolate and pin it safely. >
Thanks.
-- Kind regards, Minchan Kim -- 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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