From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH v2 6/8] kvm tools: Add rwlock wrapper Date: Mon, 30 May 2011 16:10:58 +0200 Message-ID: <20110530141058.GA12360@elte.hu> References: <20110530095451.GB8461@elte.hu> <20110530201110.f3bf20b5.yoshikawa.takuya@oss.ntt.co.jp> <1306753954.14564.92.camel@lappy> <20110530202646.eff0ea28.yoshikawa.takuya@oss.ntt.co.jp> <4DE381DB.8040804@redhat.com> <20110530114949.GD22324@elte.hu> <1306756681.14564.95.camel@lappy> <20110530122027.GJ22324@elte.hu> <4DE38C50.404@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Sasha Levin , Pekka Enberg , Takuya Yoshikawa , kvm@vger.kernel.org, asias.hejun@gmail.com, gorcunov@gmail.com, prasadjoshi124@gmail.com, "Paul E. McKenney" , takuya.yoshikawa@gmail.com To: Avi Kivity Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:50106 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745Ab1E3OLQ (ORCPT ); Mon, 30 May 2011 10:11:16 -0400 Content-Disposition: inline In-Reply-To: <4DE38C50.404@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: * Avi Kivity wrote: > On 05/30/2011 03:20 PM, Ingo Molnar wrote: > >How does this work in practice - i thought we memset() all of RAM > >during guest kernel bootup. That might have changed with the memblock > >allocator ... So the guest kernel does not touch all of that 64 GB of > >RAM, so your box wont OOM straight away? > > IIRC there never was a memset() of all RAM, at least since kvm > started booting Linux. [...] Hm, bootmem used to do a memset(). > [...] Windows has a zeroing thread which causes all of RAM to be > committed shortly after boot, though. heh, maybe they read lkml and copied my ancient idea: http://people.redhat.com/mingo/clearpage-patches/clearpage-2.3.18-J1 An earlier version had a 'zerod' (page zeroing kernel thread). This was one of my more stupid ideas btw. Thanks, Ingo