From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta12.messagelabs.com (mail6.bemta12.messagelabs.com [216.82.250.247]) by kanga.kvack.org (Postfix) with ESMTP id 6DE7B6B002D for ; Thu, 10 Nov 2011 10:31:32 -0500 (EST) Date: Thu, 10 Nov 2011 16:29:44 +0100 From: Johannes Weiner Subject: Re: [rfc 1/3] mm: vmscan: never swap under low memory pressure Message-ID: <20111110152944.GL3153@redhat.com> References: <20110808110658.31053.55013.stgit@localhost6> <4E3FD403.6000400@parallels.com> <20111102163056.GG19965@redhat.com> <20111102163141.GH19965@redhat.com> <20111107112941.0dfa07cb.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20111107112941.0dfa07cb.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: Konstantin Khlebnikov , Pekka Enberg , "linux-mm@kvack.org" , Andrew Morton , "linux-kernel@vger.kernel.org" , Wu Fengguang , Johannes Weiner , Rik van Riel , Mel Gorman , Minchan Kim , Gene Heskett On Mon, Nov 07, 2011 at 11:29:41AM +0900, KAMEZAWA Hiroyuki wrote: > On Wed, 2 Nov 2011 17:31:41 +0100 > Johannes Weiner wrote: > > > We want to prevent floods of used-once file cache pushing us to swap > > out anonymous pages. Never swap under a certain priority level. The > > availability of used-once cache pages should prevent us from reaching > > that threshold. > > > > This is needed because subsequent patches will revert some of the > > mechanisms that tried to prefer file over anon, and this should not > > result in more eager swapping again. > > > > It might also be better to keep the aging machinery going and just not > > swap, rather than staying away from anonymous pages in the first place > > and having less useful age information at the time of swapout. > > > > Signed-off-by: Johannes Weiner > > --- > > mm/vmscan.c | 2 ++ > > 1 files changed, 2 insertions(+), 0 deletions(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index a90c603..39d3da3 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -831,6 +831,8 @@ static unsigned long shrink_page_list(struct list_head *page_list, > > * Try to allocate it some swap space here. > > */ > > if (PageAnon(page) && !PageSwapCache(page)) { > > + if (priority >= DEF_PRIORITY - 2) > > + goto keep_locked; > > if (!(sc->gfp_mask & __GFP_IO)) > > goto keep_locked; > > if (!add_to_swap(page)) > > Hm, how about not scanning LRU_ANON rather than checking here ? > Add some bias to get_scan_count() or some.. > If you think to need rotation of LRU, only kswapd should do that.. Absolutely, it would require more tuning. This patch was really a 'hey, how about we do something like this? anyone tried that before?' I keep those things in mind if I pursue this further, thanks. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org