From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 12 Jun 2000 23:29:32 +0100 From: "Stephen C. Tweedie" Subject: Re: [patch] improve streaming I/O [bug in shrink_mmap()] Message-ID: <20000612232932.I15054@redhat.com> References: <87ln0abmji.fsf@atlas.iskon.hr> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ln0abmji.fsf@atlas.iskon.hr>; from zlatko@iskon.hr on Mon, Jun 12, 2000 at 11:46:09PM +0200 Sender: owner-linux-mm@kvack.org Return-Path: To: Zlatko Calusic Cc: alan@redhat.com, Linux MM List , Linux Kernel List List-ID: Hi, On Mon, Jun 12, 2000 at 11:46:09PM +0200, Zlatko Calusic wrote: > > This simple one-liner solves a long standing problem in Linux VM. > While searching for a discardable page in shrink_mmap() Linux was too > easily failing and subsequently falling back to swapping. The problem > was that shrink_mmap() counted pages from the wrong zone, and in case > of balancing a relatively smaller zone (e.g. DMA zone on a 128MB > computer) "count" would be mistakenly spent dealing with pages from > the wrong zone. The net effect of all this was spurious swapping that > hurt performance greatly. Nice --- it might also explain some of the excessive kswap CPU utilisation we've seen reported now and again. --Stephen -- 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/