From nobody Sun Feb 8 14:52:18 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zoho.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; Return-Path: Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) by mx.zohomail.com with SMTPS id 1489756940343697.4202466805773; Fri, 17 Mar 2017 06:22:20 -0700 (PDT) Received: from localhost ([::1]:48997 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1corpi-0000hZ-Qv for importer@patchew.org; Fri, 17 Mar 2017 09:22:18 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52880) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1corjo-0004fZ-4R for qemu-devel@nongnu.org; Fri, 17 Mar 2017 09:16:13 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1corjj-0000op-Ms for qemu-devel@nongnu.org; Fri, 17 Mar 2017 09:16:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39432) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1corjg-0000md-Ne; Fri, 17 Mar 2017 09:16:04 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B6C3331B319; Fri, 17 Mar 2017 13:16:04 +0000 (UTC) Received: from noname.redhat.com (ovpn-117-59.ams2.redhat.com [10.36.117.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2105617F2A; Fri, 17 Mar 2017 13:16:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com B6C3331B319 Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx05.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=kwolf@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com B6C3331B319 From: Kevin Wolf To: qemu-block@nongnu.org Date: Fri, 17 Mar 2017 14:15:45 +0100 Message-Id: <1489756546-27142-8-git-send-email-kwolf@redhat.com> In-Reply-To: <1489756546-27142-1-git-send-email-kwolf@redhat.com> References: <1489756546-27142-1-git-send-email-kwolf@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 17 Mar 2017 13:16:04 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 7/8] thread-pool: add missing qemu_bh_cancel in completion function 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: kwolf@redhat.com, qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Peter Lieven commit 3c80ca15 fixed a deadlock scenarion with nested aio_poll invocations. However, the rescheduling of the completion BH introcuded unnecessary spinn= ing in the main-loop. On very fast file backends this can even lead to the "WARNING: I/O thread spun for 1000 iterations" message popping up. Callgrind reports about 3-4% less instructions with this patch running qemu-img bench on a ramdisk based VMDK file. Fixes: 3c80ca158c96ff902a30883a8933e755988948b1 Cc: qemu-stable@nongnu.org Signed-off-by: Peter Lieven Signed-off-by: Kevin Wolf --- util/thread-pool.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/util/thread-pool.c b/util/thread-pool.c index ce6cd30..610646d 100644 --- a/util/thread-pool.c +++ b/util/thread-pool.c @@ -188,6 +188,13 @@ restart: aio_context_release(pool->ctx); elem->common.cb(elem->common.opaque, elem->ret); aio_context_acquire(pool->ctx); + + /* We can safely cancel the completion_bh here regardless of s= omeone + * else having scheduled it meanwhile because we reenter the + * completion function anyway (goto restart). + */ + qemu_bh_cancel(pool->completion_bh); + qemu_aio_unref(elem); goto restart; } else { --=20 1.8.3.1