From nobody Mon Apr 14 06:11:07 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1552064547058886.9538048023941; Fri, 8 Mar 2019 09:02:27 -0800 (PST) Received: from localhost ([127.0.0.1]:47012 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h2It4-0001Uf-V2 for importer@patchew.org; Fri, 08 Mar 2019 12:02:23 -0500 Received: from eggs.gnu.org ([209.51.188.92]:60414) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h2Ili-0003wG-JM for qemu-devel@nongnu.org; Fri, 08 Mar 2019 11:54:47 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h2Ilh-0006Q1-S4 for qemu-devel@nongnu.org; Fri, 08 Mar 2019 11:54:46 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33884) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h2Ilf-0006MU-2M; Fri, 08 Mar 2019 11:54:43 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 5732E70D67; Fri, 8 Mar 2019 16:54:42 +0000 (UTC) Received: from localhost (ovpn-117-209.ams2.redhat.com [10.36.117.209]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7D6535D786; Fri, 8 Mar 2019 16:54:33 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Fri, 8 Mar 2019 16:53:44 +0000 Message-Id: <20190308165344.10685-8-stefanha@redhat.com> In-Reply-To: <20190308165344.10685-1-stefanha@redhat.com> References: <20190308165344.10685-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Fri, 08 Mar 2019 16:54:42 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PULL 7/7] iothread: document about why we need explicit aio_poll() 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: Kevin Wolf , Peter Maydell , qemu-block@nongnu.org, "Michael S. Tsirkin" , Peter Xu , Max Reitz , Stefan Hajnoczi , =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" From: Peter Xu After consulting Paolo I know why we'd better keep the explicit aio_poll() in iothread_run(). Document it directly into the code so that future readers will know the answer from day one. Signed-off-by: Peter Xu Reviewed-by: Marc-Andr=C3=A9 Lureau Message-id: 20190306115532.23025-6-peterx@redhat.com Message-Id: <20190306115532.23025-6-peterx@redhat.com> Signed-off-by: Stefan Hajnoczi --- iothread.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/iothread.c b/iothread.c index ad64c757ac..7130be58e3 100644 --- a/iothread.c +++ b/iothread.c @@ -63,6 +63,15 @@ static void *iothread_run(void *opaque) qemu_sem_post(&iothread->init_done_sem); =20 while (iothread->running) { + /* + * Note: from functional-wise the g_main_loop_run() below can + * already cover the aio_poll() events, but we can't run the + * main loop unconditionally because explicit aio_poll() here + * is faster than g_main_loop_run() when we do not need the + * gcontext at all (e.g., pure block layer iothreads). In + * other words, when we want to run the gcontext with the + * iothread we need to pay some performance for functionality. + */ aio_poll(iothread->ctx, true); =20 /* --=20 2.20.1