Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964913AbVKBJfu (ORCPT ); Wed, 2 Nov 2005 04:35:50 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964963AbVKBJfu (ORCPT ); Wed, 2 Nov 2005 04:35:50 -0500 Received: from smtp201.mail.sc5.yahoo.com ([216.136.129.91]:60281 "HELO smtp201.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S964913AbVKBJft (ORCPT ); Wed, 2 Nov 2005 04:35:49 -0500 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=myXnFKOhNyIy2cqsu1iqFm7ngR1eh7C81Gpuh6lfkpXVvaNFGVPxZjRWQu1wlT7q2eQQi+AKV5qfP3ICGcUNV2M0j5acfcrGUHHdu+dmjMz30d2lEsbCTd2mT4gBHPHMNytnKhV2lCmWucLYI2n1yrLfSbOiuRnFQ2MQyYMmISQ= ; Message-ID: <436888E7.1060609@yahoo.com.au> Date: Wed, 02 Nov 2005 20:37:43 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Gerrit Huizenga CC: Ingo Molnar , Kamezawa Hiroyuki , Dave Hansen , Mel Gorman , "Martin J. Bligh" , Andrew Morton , kravetz@us.ibm.com, linux-mm , Linux Kernel Mailing List , lhms Subject: Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19 References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1848 Lines: 44 Gerrit Huizenga wrote: > On Wed, 02 Nov 2005 19:50:15 +1100, Nick Piggin wrote: >>Isn't the solution for your hypervisor problem to dish out pages of >>the same size that are used by the virtual machines. Doesn't this >>provide you with a nice, 100% solution that doesn't add complexity >>where it isn't needed? > > > So do you see the problem with fragementation if the hypervisor is > handing out, say, 1 MB pages? Or, more likely, something like 64 MB > pages? What are the chances that an entire 64 MB page can be freed > on a large system that has been up a while? > I see the problem, but if you want to be able to shrink memory to a given size, then you must either introduce a hard limit somewhere, or have the hypervisor hand out guest sized pages. Use zones, or Xen? > And, if you create zones, you run into all of the zone rebalancing > problems of ZONE_DMA, ZONE_NORMAL, ZONE_HIGHMEM. In that case, on > any long running system, ZONE_HOTPLUGGABLE has been overwhelmed with > random allocations, making almost none of it available. > If there are zone rebalancing problems[*], then it would be great to have more users of zones because then they will be more likely to get fixed. [*] and there are, sadly enough - see the recent patches I posted to lkml for example. But I'm fairly confident that once the particularly silly ones have been fixed, zone balancing will no longer be a derogatory term as has been thrown around (maybe rightly) in this thread! -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/