From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vivek Goyal Subject: Query about DIO/AIO WRITE throttling and ext4 serialization Date: Wed, 1 Jun 2011 17:50:49 -0400 Message-ID: <20110601215049.GC17449@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: linux-ext4@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:2680 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758812Ab1FAVuu (ORCPT ); Wed, 1 Jun 2011 17:50:50 -0400 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p51LooIV002109 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 1 Jun 2011 17:50:50 -0400 Received: from machine.usersys.redhat.com (dhcp-100-18-250.bos.redhat.com [10.16.18.250]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p51Lone9019862 for ; Wed, 1 Jun 2011 17:50:50 -0400 Content-Disposition: inline Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi, If I throttle a DIO/AIO WRITE bio at block device in a cgroup, will it lead to any kind of serialization of ext4 file system. IOW, is there any filesystem operation which will wait for that DIO/AIO WRITE to finish before other filesystem can make progress (fsync, journalling etc?) I know that for throttling of buffered WRITES I do run into serialization issues hence I was thinking of moving throttling buffered WRITE while they are entering page cache and get rid of issues related to filesystem serialization. I am not sure about DIO/AIO WRITES hence the question. Thanks Vivek