From nobody Sun Nov 9 14:51:58 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 1551873924193267.1021219213118; Wed, 6 Mar 2019 04:05:24 -0800 (PST) Received: from localhost ([127.0.0.1]:60199 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1VIU-0006rC-6d for importer@patchew.org; Wed, 06 Mar 2019 07:05:18 -0500 Received: from eggs.gnu.org ([209.51.188.92]:46471) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h1VA4-0000ak-AI for qemu-devel@nongnu.org; Wed, 06 Mar 2019 06:56:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h1V9u-0006Dv-FK for qemu-devel@nongnu.org; Wed, 06 Mar 2019 06:56:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54176) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h1V9m-00067O-Dj for qemu-devel@nongnu.org; Wed, 06 Mar 2019 06:56:20 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 39C0330718CD for ; Wed, 6 Mar 2019 11:56:16 +0000 (UTC) Received: from xz-x1.redhat.com (ovpn-12-16.pek2.redhat.com [10.72.12.16]) by smtp.corp.redhat.com (Postfix) with ESMTP id 01B865C28C; Wed, 6 Mar 2019 11:56:13 +0000 (UTC) From: Peter Xu To: qemu-devel@nongnu.org Date: Wed, 6 Mar 2019 19:55:32 +0800 Message-Id: <20190306115532.23025-6-peterx@redhat.com> In-Reply-To: <20190306115532.23025-1-peterx@redhat.com> References: <20190306115532.23025-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Wed, 06 Mar 2019 11:56:16 +0000 (UTC) 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] [PATCH v2 5/5] 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: =?UTF-8?q?Marc-Andr=C3=A9=20Lureau?= , peterx@redhat.com, Stefan Hajnoczi , Paolo Bonzini Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 --- iothread.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/iothread.c b/iothread.c index 045825a348..14e9f3779e 100644 --- a/iothread.c +++ b/iothread.c @@ -64,6 +64,15 @@ 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 2.17.1