From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 31 Jul 2002 16:23:57 -0400 From: Benjamin LaHaise Subject: Re: throttling dirtiers Message-ID: <20020731162357.Q10270@redhat.com> References: <3D479F21.F08C406C@zip.com.au> <20020731200612.GJ29537@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20020731200612.GJ29537@holomorphy.com>; from wli@holomorphy.com on Wed, Jul 31, 2002 at 01:06:12PM -0700 Sender: owner-linux-mm@kvack.org Return-Path: To: William Lee Irwin III , Andrew Morton , Rik van Riel , "linux-mm@kvack.org" List-ID: On Wed, Jul 31, 2002 at 01:06:12PM -0700, William Lee Irwin III wrote: > I'm not a fan of this kind of global decision. For example, I/O devices > may be fast enough and memory small enough to dump all memory in < 1s, > in which case dirtying most or all of memory is okay from a latency > standpoint, or it may take hours to finish dumping out 40% of memory, > in which case it should be far more eager about writeback. Why? Filling the entire ram with dirty pages is okay, and in fact you want to support that behaviour for apps that "just fit" (think big scientific apps). The only interesting point is that when you hit the limit of available memory, the system needs to block on *any* io completing and resulting in clean memory (which is reasonably low latency), not a specific io which may have very high latency. -ben -- "You will be reincarnated as a toad; and you will be much happier." -- 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/