From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx120.postini.com [74.125.245.120]) by kanga.kvack.org (Postfix) with SMTP id 620EF6B0032 for ; Thu, 16 May 2013 10:29:48 -0400 (EDT) Date: Thu, 16 May 2013 15:29:42 +0100 From: Mel Gorman Subject: Re: [PATCH 2/4] mm: pagevec: Defer deciding what LRU to add a page to until pagevec drain time Message-ID: <20130516142941.GK11497@suse.de> References: <1368440482-27909-1-git-send-email-mgorman@suse.de> <1368440482-27909-3-git-send-email-mgorman@suse.de> <20130515155330.35036978515a6d8e0fe98feb@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20130515155330.35036978515a6d8e0fe98feb@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Alexey Lyahkov , Andrew Perepechko , Robin Dong , Theodore Tso , Hugh Dickins , Rik van Riel , Johannes Weiner , Bernd Schubert , David Howells , Trond Myklebust , Linux-fsdevel , Linux-ext4 , LKML , Linux-mm On Wed, May 15, 2013 at 03:53:30PM -0700, Andrew Morton wrote: > On Mon, 13 May 2013 11:21:20 +0100 Mel Gorman wrote: > > > mark_page_accessed cannot activate an inactive page that is located on > > an inactive LRU pagevec. Hints from filesystems may be ignored as a > > result. In preparation for fixing that problem, this patch removes the > > per-LRU pagevecs and leaves just one pagevec. The final LRU the page is > > added to is deferred until the pagevec is drained. > > > > This means that fewer pagevecs are available and potentially there is > > greater contention on the LRU lock. However, this only applies in the case > > where there is an almost perfect mix of file, anon, active and inactive > > pages being added to the LRU. In practice I expect that we are adding > > stream of pages of a particular time and that the changes in contention > > will barely be measurable. > > > > ... > > > > index c612a6a..0911579 100644 > > --- a/mm/swap.c > > +++ b/mm/swap.c > > @@ -39,7 +39,7 @@ > > /* How many pages do we try to swap or page in/out together? */ > > int page_cluster; > > > > -static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs); > > +static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); > > static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); > > static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); > > > > @@ -460,13 +460,18 @@ EXPORT_SYMBOL(mark_page_accessed); > > */ > > The comment preceding __lru_cache_add() needs an update. > This? ---8<--- diff --git a/mm/swap.c b/mm/swap.c index 05944d4..ac23602 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -489,12 +489,10 @@ void mark_page_accessed(struct page *page) EXPORT_SYMBOL(mark_page_accessed); /* - * Order of operations is important: flush the pagevec when it's already - * full, not when adding the last page, to make sure that last page is - * not added to the LRU directly when passed to this function. Because - * mark_page_accessed() (called after this when writing) only activates - * pages that are on the LRU, linear writes in subpage chunks would see - * every PAGEVEC_SIZE page activated, which is unexpected. + * Queue the page for addition to the LRU via pagevec. The decision on whether + * to add the page to the [in]active [file|anon] list is deferred until the + * pagevec is drained. This gives a chance for the caller of __lru_cache_add() + * have the page added to the active list using mark_page_accessed(). */ void __lru_cache_add(struct page *page) { -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org