From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 16 Jul 2001 21:27:02 -0300 (BRT) From: Marcelo Tosatti Subject: Re: [PATCH] Separate global/perzone inactive/free shortage 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: Rik van Riel Cc: Kanoj Sarcar , lkml , Dirk Wetter , Mike Galbraith , linux-mm@kvack.org, "Stephen C. Tweedie" List-ID: On Mon, 16 Jul 2001, Rik van Riel wrote: > On Mon, 16 Jul 2001, Kanoj Sarcar wrote: > > > Just a quick note. A per-zone page reclamation > > method like this was what I had advocated and sent > > patches to Linus for in the 2.3.43 time frame or so. > > I think later performance work ripped out that work. > > Yes, the system ended up swapping as soon as the first zone > was filled up and after that would fill up the other zones; > the way the system stabilised was cycling through the pages > of one zone and leaving the lower zones alone. > > This reduced the amount of available VM of a 1GB system > to 128MB, which is somewhat suboptimal ;) > > What we learned from that is that we need to have some > way to auto-balance the reclaiming, keeping the objective > of evicting the least used page from RAM in mind. > > > I guess the problem is that a lot of the different > > page reclamation schemes first of all do not know > > how to reclaim pages for a specific zone, > > > try_to_swap_out is a good example, which can be solved > > by rmaps. > > Indeed. Most of the time things go right, but the current > system cannot cope at all when things go wrong. I think we > really want things like rmaps and more sturdy reclaiming > mechanisms to cope with these worst cases (and also to make > the common case easier to get right). As I said to Kanoj, I agree that we really want rmaps to fix that thing right. Now I don't see any other way for fixing that on _2.4_ except something similar to the patch I posted. That patch can still have problems in practice, but fundamentally _it is the right thing_, IMO. -- 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/