From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55133) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X1Z8C-0000Ka-Fc for qemu-devel@nongnu.org; Mon, 30 Jun 2014 06:48:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1X1Z83-0004gi-Df for qemu-devel@nongnu.org; Mon, 30 Jun 2014 06:48:16 -0400 Received: from mail-we0-x22d.google.com ([2a00:1450:400c:c03::22d]:64115) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1X1Z83-0004fP-5D for qemu-devel@nongnu.org; Mon, 30 Jun 2014 06:48:07 -0400 Received: by mail-we0-f173.google.com with SMTP id t60so8015437wes.4 for ; Mon, 30 Jun 2014 03:48:05 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <53B14064.8010600@redhat.com> Date: Mon, 30 Jun 2014 12:48:04 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <53ADE6F8.1070303@redhat.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] The first function called after migration for a block device List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Xiongzi Ge Cc: qemu-devel@nongnu.org Il 28/06/2014 00:54, Xiongzi Ge ha scritto: > Hi Paolo, > > Thanks. I found a function called bdrv_invalidate_cache() in qcow2.c. > After migration, it will be called to invalidate the cache of the block > device? Let me quote again: >> This function has *nothing* to do with the guest OS's >> cache. That cache is managed by the guest OS and, as I have already >> told you multiple times, there is *nothing* that QEMU can do about it. >> >> All you can do is use O_DIRECT in the guest. Did you even *try* to understand this?!? Paolo