From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: Re: [PATCH] kvm tools: Make the whole guest memory mergeable Date: Fri, 16 Dec 2011 09:23:08 +0200 Message-ID: <1324020188.4496.17.camel@lappy> References: <1323997263-2031-1-git-send-email-zanghongyong@huawei.com> <1324014621.4496.3.camel@lappy> <4EEAED0E.5050106@huawei.com> 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: Zang Hongyong Return-path: Received: from mail-ee0-f46.google.com ([74.125.83.46]:52029 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751293Ab1LPHXO (ORCPT ); Fri, 16 Dec 2011 02:23:14 -0500 Received: by eekc4 with SMTP id c4so2918083eek.19 for ; Thu, 15 Dec 2011 23:23:13 -0800 (PST) In-Reply-To: <4EEAED0E.5050106@huawei.com> Sender: kvm-owner@vger.kernel.org List-ID: 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. -- Sasha.