From patchwork Thu Aug 6 13:17:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 277023 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44413C433E0 for ; Thu, 6 Aug 2020 13:19:14 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3221A2313B for ; Thu, 6 Aug 2020 13:19:14 +0000 (UTC) Authentication-Results: mail.kernel.org; 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Thu, 6 Aug 2020 13:18:07 +0000 (UTC) Received: from localhost (ovpn-114-7.ams2.redhat.com [10.36.114.7]) by smtp.corp.redhat.com (Postfix) with ESMTP id 7DF977B93D; Thu, 6 Aug 2020 13:18:03 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Subject: [PATCH v3 0/3] aio-posix: keep aio_notify_me disabled during polling Date: Thu, 6 Aug 2020 14:17:59 +0100 Message-Id: <20200806131802.569478-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.120; envelope-from=stefanha@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/06 00:24:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Paolo Bonzini , qemu-block@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" v3: * Use smp_wmb() in aio_notify_accept() [Paolo] * Flatten if statement in aio_poll() [Paolo] v2: * Added smp_mb() in aio_notify_accept() [Paolo] * Added comments about memory barrier pairing [Paolo] * Eliminated extra aio_compute_timeout() before calling ppoll() This patch series eliminates ctx->notifier EventNotifier activity when aio_poll() is in polling mode. There is no need to use the EventNotifier since a polling handler can detect that aio_notify() has been called by monitoring a field in memory instead. Optimizing out the EventNotifier calls improves null-co random read 4KB iodepth=1 IOPS by 18%. I have not modified docs/spin/aio_notify*.promela because I'm not familiar with the SPIN model checker. Stefan Hajnoczi (3): async: rename event_notifier_dummy_cb/poll() async: always set ctx->notified in aio_notify() aio-posix: keep aio_notify_me disabled during polling util/aio-posix.c | 47 +++++++++++++++++++++++++---------------------- util/async.c | 36 +++++++++++++++++++++++------------- 2 files changed, 48 insertions(+), 35 deletions(-) -- 2.26.2