From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx143.postini.com [74.125.245.143]) by kanga.kvack.org (Postfix) with SMTP id CD5A36B007E for ; Mon, 9 Apr 2012 15:18:37 -0400 (EDT) Received: by iajr24 with SMTP id r24so8470940iaj.14 for ; Mon, 09 Apr 2012 12:18:37 -0700 (PDT) Date: Mon, 9 Apr 2012 12:18:14 -0700 (PDT) From: Hugh Dickins Subject: Re: [RFC PATCH 0/2] Removal of lumpy reclaim In-Reply-To: <4F8325FB.80409@redhat.com> Message-ID: References: <1332950783-31662-1-git-send-email-mgorman@suse.de> <20120406123439.d2ba8920.akpm@linux-foundation.org> <4F8325FB.80409@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Andrew Morton , Mel Gorman , Linux-MM , LKML , Konstantin Khlebnikov On Mon, 9 Apr 2012, Rik van Riel wrote: > On 04/06/2012 04:31 PM, Hugh Dickins wrote: > > On Fri, 6 Apr 2012, Andrew Morton wrote: > > > On Wed, 28 Mar 2012 17:06:21 +0100 > > > Mel Gorman wrote: > > > > > > > (cc'ing active people in the thread "[patch 68/92] mm: forbid > > > > lumpy-reclaim > > > > in shrink_active_list()") > > > > > > > > In the interest of keeping my fingers from the flames at LSF/MM, I'm > > > > releasing an RFC for lumpy reclaim removal. > > > > > > I grabbed them, thanks. > > > > I do have a concern with this: I was expecting lumpy reclaim to be > > replaced by compaction, and indeed it is when CONFIG_COMPACTION=y. > > But when CONFIG_COMPACTION is not set, we're back to 2.6.22 in > > relying upon blind chance to provide order>0 pages. > > Is this an issue for any architecture? Dunno about any architecture as a whole; but I'd expect users of SLOB or TINY config options to want to still use lumpy rather than the more efficient but weightier COMPACTION+MIGRATION. Though "size migrate.o compaction.o" on my 32-bit config does not reach 8kB, so maybe it's not a big deal after all. > > I could see NOMMU being unable to use compaction, but Yes, COMPACTION depends on MMU. > chances are lumpy reclaim would be sufficient for that > configuration, anyway... That's an argument for your patch in 3.4-rc, which uses lumpy only when !COMPACTION_BUILD. But here we're worrying about Mel's patch, which removes the lumpy code completely. Hugh -- 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