From patchwork Mon Dec 19 08:51:25 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dou Liyang X-Patchwork-Id: 707011 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3thvx20Kmbz9t1F for ; Mon, 19 Dec 2016 19:59:18 +1100 (AEDT) Received: from localhost ([::1]:44088 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cItmt-0000iM-UW for incoming@patchwork.ozlabs.org; Mon, 19 Dec 2016 03:59:16 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58410) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cItgD-0004B8-AV for qemu-devel@nongnu.org; Mon, 19 Dec 2016 03:52:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cItgB-00081S-Ry for qemu-devel@nongnu.org; Mon, 19 Dec 2016 03:52:21 -0500 Received: from [59.151.112.132] (port=17864 helo=heian.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cItgB-0007mf-DZ for qemu-devel@nongnu.org; Mon, 19 Dec 2016 03:52:19 -0500 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="14050866" Received: from unknown (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 19 Dec 2016 16:52:03 +0800 Received: from G08CNEXCHPEKD02.g08.fujitsu.local (unknown [10.167.33.83]) by cn.fujitsu.com (Postfix) with ESMTP id 187F94670074; Mon, 19 Dec 2016 16:52:00 +0800 (CST) Received: from localhost.localdomain.localdomain (10.167.226.106) by G08CNEXCHPEKD02.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.319.2; Mon, 19 Dec 2016 16:52:04 +0800 From: Dou Liyang To: , , , , , , Date: Mon, 19 Dec 2016 16:51:25 +0800 Message-ID: <1482137486-9843-4-git-send-email-douly.fnst@cn.fujitsu.com> X-Mailer: git-send-email 2.5.5 In-Reply-To: <1482137486-9843-1-git-send-email-douly.fnst@cn.fujitsu.com> References: <1482137486-9843-1-git-send-email-douly.fnst@cn.fujitsu.com> MIME-Version: 1.0 X-Originating-IP: [10.167.226.106] X-yoursite-MailScanner-ID: 187F94670074.ADEA5 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: douly.fnst@cn.fujitsu.com X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 59.151.112.132 Subject: [Qemu-devel] [PATCH RFC v2 3/4] block/qapi: acquire a reference instead of a lock during querying blockstats X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: izumi.taku@jp.fujitsu.com, caoj.fnst@cn.fujitsu.com, fanc.fnst@cn.fujitsu.com, qemu-devel@nongnu.org, douly.fnst@cn.fujitsu.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" This patch works to improve the performance of the query requests. From the commit 13344f3a, it adds a lock to make query-blockstats safe by the aio_context_acquire(). the qmp_query_blockstats func requires/releases the AioContext lock, which takes some time and blocks the I/O processing. It affects the performance, especially in the multi-disks guests. As the low-level details of block statistics inside QEMU, we can acquire a reference instead of the lock. Signed-off-by: Dou Liyang --- block/qapi.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/block/qapi.c b/block/qapi.c index bc622cd..2262918 100644 --- a/block/qapi.c +++ b/block/qapi.c @@ -457,17 +457,21 @@ static BlockStats *bdrv_query_bds_stats(const BlockDriverState *bs, } static BlockStats *bdrv_query_stats(BlockBackend *blk, - const BlockDriverState *bs, + BlockDriverState *bs, bool query_backing) { BlockStats *s; + bdrv_ref(bs); s = bdrv_query_bds_stats(bs, query_backing); + bdrv_unref(bs); if (blk) { + blk_ref(blk); s->has_device = true; s->device = g_strdup(blk_name(blk)); bdrv_query_blk_stats(s->stats, blk); + blk_unref(blk); } return s; @@ -523,13 +527,8 @@ BlockStatsList *qmp_query_blockstats(bool has_query_nodes, while (next_query_bds(&blk, &bs, query_nodes)) { BlockStatsList *info = g_malloc0(sizeof(*info)); - AioContext *ctx = blk ? blk_get_aio_context(blk) - : bdrv_get_aio_context(bs); - aio_context_acquire(ctx); info->value = bdrv_query_stats(blk, bs, !query_nodes); - aio_context_release(ctx); - *p_next = info; p_next = &info->next; }