From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56585) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cJ0ro-0007VQ-4Y for qemu-devel@nongnu.org; Mon, 19 Dec 2016 11:32:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cJ0rk-000322-6y for qemu-devel@nongnu.org; Mon, 19 Dec 2016 11:32:48 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57982) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cJ0rk-00031p-1c for qemu-devel@nongnu.org; Mon, 19 Dec 2016 11:32:44 -0500 Date: Tue, 20 Dec 2016 00:32:40 +0800 From: Fam Zheng Message-ID: <20161219163214.GA9801@lemon> References: <1482137486-9843-1-git-send-email-douly.fnst@cn.fujitsu.com> <20161219150230.GA20757@stefanha-x1.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161219150230.GA20757@stefanha-x1.localdomain> Subject: Re: [Qemu-devel] [PATCH RFC v2 0/4] block/qapi: refactor and optimize the qmp_query_blockstats() List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi Cc: Dou Liyang , stefanha@redhat.com, kwolf@redhat.com, armbru@redhat.com, mreitz@redhat.com, eblake@redhat.com, izumi.taku@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com, fanc.fnst@cn.fujitsu.com, qemu-devel@nongnu.org On Mon, 12/19 15:02, Stefan Hajnoczi wrote: > On Mon, Dec 19, 2016 at 04:51:22PM +0800, Dou Liyang wrote: > > These patches aim to refactor the qmp_query_blockstats() and > > improve the performance by reducing the running time of it. > > > > qmp_query_blockstats() is used to monitor the blockstats, it > > querys all the graph_bdrv_states or monitor_block_backends. > > > > There are the two jobs: > > > > 1 For the performance: > > > > 1.1 the time it takes(ns) in each time: > > the disk numbers | 10 | 500 > > ------------------------------------- > > before these patches | 19429 | 667722 > > after these patches | 17516 | 557044 > > > > 1.2 the I/O performance is degraded(%) during the monitor: > > > > the disk numbers | 10 | 500 > > ------------------------------------- > > before these patches | 1.3 | 14.2 > > after these patches | 0.8 | 9.1 > > Do you know what is consuming the remaining 9.1%? > > I'm surprised to see such a high performance impact caused by a QMP > command. If it's "performance is 9.1% worse only during the 557044 ns when the QMP command is being processed", it's probably becaues the main loop is stalled a bit, and it's not a big problem. I'd be very surprised if the degradation is more longer than that. Fam > > Please post your QEMU command-line.