From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 20 Jun 2000 13:18:38 -0300 (BRST) From: Rik van Riel Subject: Re: shrink_mmap() change in ac-21 In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Andrea Arcangeli Cc: Jamie Lokier , Zlatko Calusic , alan@redhat.com, linux-mm@kvack.org, linux-kernel@vger.rutgers.edu List-ID: On Tue, 20 Jun 2000, Andrea Arcangeli wrote: > On Mon, 19 Jun 2000, Jamie Lokier wrote: > > >if those wrong zones are quite full. If the DMA zone desparately needs > >free pages and keeps needing them, isn't it good to encourage future > >non-DMA allocations to use another zone? Removing pages from other > > After some time the DMA zone will be full again anyway and you > payed a cost that consists in throwing away unrelated innocent > pages. I'm not convinced it's the right thing to do. I didn't know for sure either until I tested -ac21 on my 192MB workstation. The bursts kswapd went through when it was freeing DMA memory (and 8MB of other memory) have convinced me that this is not a good idea. Also, since kswapd stops when all zones have free_pages above pages_low and we'll free up to pages_high pages of one zone, it means that we'll: - allocate the next series of pages from that one zone with tons of unused pages - wake up kswapd so we'll free the *next* unused pages from that zone when we run out of the current batch - rinse and repeat This means we'll do a *lot* more allocations from the less loaded zones than from the other zone, with a few (short) interruptions by kswapd. Also, there's no need to throw away data early. Of course, once we have a scavenge list (in the active inactive scavenge list VM) this whole point will be moot and we just want to avoid doing too much IO at once). regards, Rik -- The Internet is not a network of computers. It is a network of people. That is its real strength. Wanna talk about the kernel? irc.openprojects.net / #kernelnewbies http://www.conectiva.com/ http://www.surriel.com/ -- 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.eu.org/Linux-MM/