From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 Jul 2001 14:42:19 -0400 (EDT) From: Dirk Wetter Subject: Re: [PATCH] Separate global/perzone inactive/free shortage In-Reply-To: <20010716141915.C28023@redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Stephen C. Tweedie" Cc: Mike Galbraith , Marcelo Tosatti , Rik van Riel , linux-mm@kvack.org List-ID: On Mon, 16 Jul 2001, Stephen C. Tweedie wrote: > Hi, > > > On Sat, 14 Jul 2001, Marcelo Tosatti wrote: > > > On highmem machines, wouldn't it save a LOT of time to prevent allocation > > of ZONE_DMA as VM pages? Or, if we really need to, get those pages into > > the swapcache instantly? Crawling through nearly 4 gig of VM looking for > > 16 MB of ram has got to be very expensive. Besides, those pages are just > > too precious to allow some user task to sit on them. > > Can't we balance that automatically? > > Why not just round-robin between the eligible zones when allocating, > biasing each zone based on size? On a 4GB box you'd basically end up > doing 3 times as many allocations from the highmem zone as the normal > zone and only very occasionally would you try to dig into the dma > zone. But on a 32MB box you would automatically spread allocations > 50/50 between normal and dma, and on a 20MB box you would be biased in > favour of allocating dma pages. how good would be the one-size-fits-all approach? certainly i would like to have the best memory performance for my 4GB boxes, so does the guy with the 20MB or 32MB box. why not having yet another kernel config option ;-) ? cheers, ~dirkw -- 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/