From patchwork Mon Aug 17 15:16:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 276258 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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham 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 207C7C433E1 for ; Mon, 17 Aug 2020 15:55:09 +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 CE12220888 for ; Mon, 17 Aug 2020 15:55:08 +0000 (UTC) Authentication-Results: mail.kernel.org; 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Mon, 17 Aug 2020 15:16:44 +0000 (UTC) Received: from localhost (ovpn-112-42.ams2.redhat.com [10.36.112.42]) by smtp.corp.redhat.com (Postfix) with ESMTP id BEA757A21D; Mon, 17 Aug 2020 15:16:40 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org, Peter Maydell Subject: [PULL 1/3] async: rename event_notifier_dummy_cb/poll() Date: Mon, 17 Aug 2020 16:16:32 +0100 Message-Id: <20200817151634.35563-2-stefanha@redhat.com> In-Reply-To: <20200817151634.35563-1-stefanha@redhat.com> References: <20200817151634.35563-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=216.205.24.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/17 02:47:08 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 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_H5=-1, 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 , Kevin Wolf , Eduardo Habkost , qemu-block@nongnu.org, Max Reitz , Stefan Hajnoczi , Cleber Rosa , Paolo Bonzini , =?utf-8?q?Ph?= =?utf-8?q?ilippe_Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" The event_notifier_*() prefix can be confused with the EventNotifier APIs that are also called event_notifier_*(). Rename the functions to aio_context_notifier_*() to make it clear that they relate to the AioContext::notifier field. Signed-off-by: Stefan Hajnoczi Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Paolo Bonzini Message-id: 20200806131802.569478-2-stefanha@redhat.com Signed-off-by: Stefan Hajnoczi --- util/async.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/util/async.c b/util/async.c index 1319eee3bc..d9f987e133 100644 --- a/util/async.c +++ b/util/async.c @@ -445,12 +445,12 @@ static void aio_timerlist_notify(void *opaque, QEMUClockType type) aio_notify(opaque); } -static void event_notifier_dummy_cb(EventNotifier *e) +static void aio_context_notifier_dummy_cb(EventNotifier *e) { } /* Returns true if aio_notify() was called (e.g. a BH was scheduled) */ -static bool event_notifier_poll(void *opaque) +static bool aio_context_notifier_poll(void *opaque) { EventNotifier *e = opaque; AioContext *ctx = container_of(e, AioContext, notifier); @@ -508,8 +508,8 @@ AioContext *aio_context_new(Error **errp) aio_set_event_notifier(ctx, &ctx->notifier, false, - event_notifier_dummy_cb, - event_notifier_poll); + aio_context_notifier_dummy_cb, + aio_context_notifier_poll); #ifdef CONFIG_LINUX_AIO ctx->linux_aio = NULL; #endif From patchwork Mon Aug 17 15:16:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 276266 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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=ham 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 3F5ACC433E1 for ; Mon, 17 Aug 2020 15:43:18 +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 EB81020760 for ; 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Mon, 17 Aug 2020 15:16:49 +0000 (UTC) Received: from localhost (ovpn-112-42.ams2.redhat.com [10.36.112.42]) by smtp.corp.redhat.com (Postfix) with ESMTP id C380F10021AA; Mon, 17 Aug 2020 15:16:45 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org, Peter Maydell Subject: [PULL 2/3] async: always set ctx->notified in aio_notify() Date: Mon, 17 Aug 2020 16:16:33 +0100 Message-Id: <20200817151634.35563-3-stefanha@redhat.com> In-Reply-To: <20200817151634.35563-1-stefanha@redhat.com> References: <20200817151634.35563-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=stefanha@redhat.com X-Mimecast-Spam-Score: 0.002 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=205.139.110.61; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/17 05:03:47 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 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_H2=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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 , Kevin Wolf , Eduardo Habkost , qemu-block@nongnu.org, Max Reitz , Stefan Hajnoczi , Cleber Rosa , Paolo Bonzini , =?utf-8?q?Ph?= =?utf-8?q?ilippe_Mathieu-Daud=C3=A9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" aio_notify() does not set ctx->notified when called with ctx->aio_notify_me disabled. Therefore aio_notify_me needs to be enabled during polling. This is suboptimal since expensive event_notifier_set(&ctx->notifier) and event_notifier_test_and_clear(&ctx->notifier) calls are required when ctx->aio_notify_me is enabled. Change aio_notify() so that aio->notified is always set, regardless of ctx->aio_notify_me. This will make polling cheaper since ctx->aio_notify_me can remain disabled. Move the event_notifier_test_and_clear() to the fd handler function (which is now no longer an empty function so "dummy" has been dropped from its name). The next patch takes advantage of this by optimizing polling in util/aio-posix.c. Signed-off-by: Stefan Hajnoczi Reviewed-by: Paolo Bonzini Reviewed-by: Philippe Mathieu-Daudé Message-id: 20200806131802.569478-3-stefanha@redhat.com [Paolo Bonzini pointed out that the smp_wmb() in aio_notify_accept() should be smp_wb() but the comment should be smp_wmb() instead of smp_wb(). Fixed. --Stefan] Signed-off-by: Stefan Hajnoczi --- util/async.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) diff --git a/util/async.c b/util/async.c index d9f987e133..4266745dee 100644 --- a/util/async.c +++ b/util/async.c @@ -419,25 +419,32 @@ LuringState *aio_get_linux_io_uring(AioContext *ctx) void aio_notify(AioContext *ctx) { - /* Write e.g. bh->scheduled before reading ctx->notify_me. Pairs + /* + * Write e.g. bh->flags before writing ctx->notified. Pairs with smp_mb in + * aio_notify_accept. + */ + smp_wmb(); + atomic_set(&ctx->notified, true); + + /* + * Write ctx->notified before reading ctx->notify_me. Pairs * with smp_mb in aio_ctx_prepare or aio_poll. */ smp_mb(); if (atomic_read(&ctx->notify_me)) { event_notifier_set(&ctx->notifier); - atomic_mb_set(&ctx->notified, true); } } void aio_notify_accept(AioContext *ctx) { - if (atomic_xchg(&ctx->notified, false) -#ifdef WIN32 - || true -#endif - ) { - event_notifier_test_and_clear(&ctx->notifier); - } + atomic_set(&ctx->notified, false); + + /* + * Write ctx->notified before reading e.g. bh->flags. Pairs with smp_wmb + * in aio_notify. + */ + smp_mb(); } static void aio_timerlist_notify(void *opaque, QEMUClockType type) @@ -445,8 +452,11 @@ static void aio_timerlist_notify(void *opaque, QEMUClockType type) aio_notify(opaque); } -static void aio_context_notifier_dummy_cb(EventNotifier *e) +static void aio_context_notifier_cb(EventNotifier *e) { + AioContext *ctx = container_of(e, AioContext, notifier); + + event_notifier_test_and_clear(&ctx->notifier); } /* Returns true if aio_notify() was called (e.g. a BH was scheduled) */ @@ -508,7 +518,7 @@ AioContext *aio_context_new(Error **errp) aio_set_event_notifier(ctx, &ctx->notifier, false, - aio_context_notifier_dummy_cb, + aio_context_notifier_cb, aio_context_notifier_poll); #ifdef CONFIG_LINUX_AIO ctx->linux_aio = NULL;