From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zang Hongyong Subject: Re: [PATCH] kvm tools: Make the whole guest memory mergeable Date: Fri, 16 Dec 2011 16:36:43 +0800 Message-ID: <4EEB031B.2020806@huawei.com> References: <1323997263-2031-1-git-send-email-zanghongyong@huawei.com> <1324014621.4496.3.camel@lappy> <4EEAED0E.5050106@huawei.com> <1324020188.4496.17.camel@lappy> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7BIT Cc: kvm@vger.kernel.org, penberg@kernel.org, xiaowei.yang@huawei.com, hanweidong@huawei.com, wusongwei@huawei.com, kongbo@huawei.com To: Sasha Levin Return-path: Received: from szxga01-in.huawei.com ([119.145.14.64]:53391 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751229Ab1LPIiT (ORCPT ); Fri, 16 Dec 2011 03:38:19 -0500 Received: from huawei.com (szxga05-in [172.24.2.49]) by szxga05-in.huawei.com (iPlanet Messaging Server 5.2 HotFix 2.14 (built Aug 8 2006)) with ESMTP id <0LWA00LGGFXOPE@szxga05-in.huawei.com> for kvm@vger.kernel.org; Fri, 16 Dec 2011 16:37:00 +0800 (CST) Received: from szxrg02-dlp.huawei.com ([172.24.2.119]) by szxga05-in.huawei.com (iPlanet Messaging Server 5.2 HotFix 2.14 (built Aug 8 2006)) with ESMTP id <0LWA00IG2FXLC8@szxga05-in.huawei.com> for kvm@vger.kernel.org; Fri, 16 Dec 2011 16:37:00 +0800 (CST) In-reply-to: <1324020188.4496.17.camel@lappy> Sender: kvm-owner@vger.kernel.org List-ID: 于 2011/12/16,星期五 15:23, Sasha Levin 写道: > On Fri, 2011-12-16 at 15:02 +0800, Zang Hongyong wrote: >> 于 2011/12/16,星期五 13:50, Sasha Levin 写道: >>> On Fri, 2011-12-16 at 09:01 +0800, zanghongyong@huawei.com wrote: >>>> If a guest's ram_size exceeds KVM_32BIT_GAP_START, the corresponding kvm tool's >>>> virtual address size should be (ram_size + KVM_32BIT_GAP_SIZE), rather than ram_size. >>> You're right. >>> >>> There are more places than just the madvise() code which make the same >>> error you've spotted (for example, the memslot allocation code), so >>> instead of trying to fix all of them I'd suggest to just update ram_size >>> in kvm__arch_init() before allocating everything - that should fix all >>> of them at once. >>> >> Yes. There are other scenarios with the same error. >> However ram_size sometimes means real guest ram size, and sometimes >> means virtual address >> size of kvm tool's user space. Shall we define a new variable? > Let's keep it simple. If the user requests more than RAM than > KVM_32BIT_GAP_START just increase it by KVM_32BIT_GAP_SIZE, this way > mapped size == guest size always (we can madvise(MADV_DONTNEED) the gap > in the mmapped ram). > > Since a user which requests more than KVM_32BIT_GAP_START will have to > be on 64bit host anyway, there shouldn't be any issue with that. > Do you mean increase *kvm->ram_size* by KVM_32BIT_GAP_SIZE? but sometimes kvm->ram_size stands for guest physical ram size (for example in kvm__init_ram() code).