From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 9C06F6B0089 for ; Wed, 1 Dec 2010 03:24:29 -0500 (EST) Subject: Re: [PATCH 1/3] mm: kswapd: Stop high-order balancing when any suitable zone is balanced From: Shaohua Li In-Reply-To: <20101201164647.ABD7.A69D9226@jp.fujitsu.com> References: <20101201122638.ABBF.A69D9226@jp.fujitsu.com> <1291189227.12777.79.camel@sli10-conroe> <20101201164647.ABD7.A69D9226@jp.fujitsu.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 01 Dec 2010 16:24:26 +0800 Message-ID: <1291191866.12777.82.camel@sli10-conroe> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: Mel Gorman , Simon Kirby , Dave Hansen , linux-mm , linux-kernel List-ID: On Wed, 2010-12-01 at 15:52 +0800, KOSAKI Motohiro wrote: > > > > > we can't make > > > > > perfect VM heuristics obviously, then we need to compare pros/cons. > > > > if you don't care about small system, let's consider a NORMAL i386 > > > > system with 896m normal zone, and 896M*3 high zone. normal zone will > > > > quickly exhaust by high order high zone allocation, leave a latter > > > > allocation which does need normal zone fail. > > > > > > Not happen. slab don't allocate from highmem and page cache allocation > > > is always using order-0. When happen high order high zone allocation? > > ok, thanks, I missed this. then how about a x86_64 box with 896M DMA32 > > and 896*3M NORMAL? some pci devices can only dma to DMA32 zone. > > First, DMA32 is 4GB. Second, modern high end system don't use 32bit PCI > device. Third, while we are thinking desktop users, 4GB is not small > room. nowadays, typical desktop have only 2GB or 4GB memory. DMA32 isn't 4G, because there is hole under 4G for PCI bars. I don't think 32 bit PCI device is rare too. But anyway, if you insist this isn't a big issue, I'm ok. -- 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/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org