From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58952C433EF for ; Thu, 3 Feb 2022 18:24:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353483AbiBCSYu (ORCPT ); Thu, 3 Feb 2022 13:24:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56962 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353468AbiBCSYt (ORCPT ); Thu, 3 Feb 2022 13:24:49 -0500 Received: from mail-wm1-x335.google.com (mail-wm1-x335.google.com [IPv6:2a00:1450:4864:20::335]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 80AF0C061744 for ; Thu, 3 Feb 2022 10:24:48 -0800 (PST) Received: by mail-wm1-x335.google.com with SMTP id k6-20020a05600c1c8600b003524656034cso2351109wms.2 for ; Thu, 03 Feb 2022 10:24:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=Nbb/JonlYt2gwQTccH2YTHZ8fFvVyRbc8c63+KA/SXs=; b=tIGn+9IvEdbkXn5xnNLy09gK3SY2EFeBj/BT39em5zIXMjreIH0iirlTjng4muT1re iqgntSWn1lpNoVerckRjRAvdhLtLuHRymFX88dZi47LvqLyQFnGVfmf1H0AyReqDmx/n BVQvPiqTc63TJTO75Y/SmZrRXGCWz1QEGbVZA/VP7r91FFphT1FX9pS2MWkuZR5viui8 fpvguOV37Xq9Zlxlqm6EsKxFrhCtXzdLEUtPO6EUUEkETmysOeQiRlj1Aaslysc0afL3 tJgWWVpfWQEF+juElhCDyExWrDjLzjJ9YwYnXInIhchz30cDe92A1MC2PQWwdAuM+NOI aR+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=Nbb/JonlYt2gwQTccH2YTHZ8fFvVyRbc8c63+KA/SXs=; b=sT/Kbnkw7wNMeVwQzojULUwK9TWhUK7iEz7mxZ6LLQq3vnP0DG9cSWnwm6s+BOQrbZ u/cvI6zBB7KlwB/xCCJNeH3HRsWvk631JAl4ORi0nV5QAV1iju3xLXurNYm6HuDTRykR 2Y18Jc75R7HH1IlZW1/lmWpMJEa3jismozv1X2tC3KT8/0zek5tKQqYklOXVvaQ213eR 5nFakBd4Q7b2pE7MVAhefDaHNDuGSECkU0k6cnAINF+nmhyWP/Wsl4h8OugzICqy3Fwk LncmoX/8kGLlIuD5VRqxfKsvgojDie9jrGIIlam+saM2G+Qq948CDp/lesU7CwbFYCiS f7xQ== X-Gm-Message-State: AOAM533UC2PmWgMFtmcImqLW3E3KQ1qyXTrU++/jEZv8188U0KLWTfTj ZeBfE25vLzDURxG76x+9ak9Q+icHK8Wmrw== X-Google-Smtp-Source: ABdhPJy8kFjgZA7GepNZjH7o49H9W94lbEP8JvFAcXl7hMwg0rlZPQMT0bcsqkgE3yBPSknYYP+iTA== X-Received: by 2002:a7b:c0c8:: with SMTP id s8mr11511762wmh.3.1643912687002; Thu, 03 Feb 2022 10:24:47 -0800 (PST) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6d:f804:0:28c2:5854:c832:e580]) by smtp.gmail.com with ESMTPSA id h18sm3540056wro.9.2022.02.03.10.24.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Feb 2022 10:24:46 -0800 (PST) From: Usama Arif To: io-uring@vger.kernel.org, axboe@kernel.dk, asml.silence@gmail.com, linux-kernel@vger.kernel.org Cc: fam.zheng@bytedance.com, Usama Arif Subject: [PATCH v4 3/3] io_uring: avoid ring quiesce for IORING_REGISTER_EVENTFD_ASYNC Date: Thu, 3 Feb 2022 18:24:41 +0000 Message-Id: <20220203182441.692354-4-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220203182441.692354-1-usama.arif@bytedance.com> References: <20220203182441.692354-1-usama.arif@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org This is done using the RCU data structure (io_ev_fd). eventfd_async is moved from io_ring_ctx to io_ev_fd which is RCU protected hence avoiding ring quiesce which is much more expensive than an RCU lock. io_should_trigger_evfd is already under rcu_read_lock so there is no extra RCU read-side critical section needed. Signed-off-by: Usama Arif --- fs/io_uring.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 7a8f4ac7a785..e287fc61879f 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -329,6 +329,7 @@ struct io_submit_state { struct io_ev_fd { struct eventfd_ctx *cq_ev_fd; struct io_ring_ctx *ctx; + unsigned int eventfd_async: 1; struct rcu_head rcu; }; @@ -341,7 +342,6 @@ struct io_ring_ctx { unsigned int flags; unsigned int compat: 1; unsigned int drain_next: 1; - unsigned int eventfd_async: 1; unsigned int restricted: 1; unsigned int off_timeout_used: 1; unsigned int drain_active: 1; @@ -1747,7 +1747,7 @@ static void io_eventfd_signal(struct io_ring_ctx *ctx) if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED) goto out; - if (!ctx->eventfd_async || io_wq_current_is_worker()) + if (!ev_fd->eventfd_async || io_wq_current_is_worker()) eventfd_signal(ev_fd->cq_ev_fd, 1); out: @@ -9368,7 +9368,8 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx, return done ? done : err; } -static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg) +static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg, + unsigned int eventfd_async) { struct io_ev_fd *ev_fd; __s32 __user *fds = arg; @@ -9398,6 +9399,7 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg) goto out; } ev_fd->ctx = ctx; + ev_fd->eventfd_async = eventfd_async; rcu_assign_pointer(ctx->io_ev_fd, ev_fd); ret = 0; @@ -11013,6 +11015,7 @@ static bool io_register_op_must_quiesce(int op) case IORING_UNREGISTER_FILES: case IORING_REGISTER_FILES_UPDATE: case IORING_REGISTER_EVENTFD: + case IORING_REGISTER_EVENTFD_ASYNC: case IORING_UNREGISTER_EVENTFD: case IORING_REGISTER_PROBE: case IORING_REGISTER_PERSONALITY: @@ -11113,17 +11116,16 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode, ret = io_register_files_update(ctx, arg, nr_args); break; case IORING_REGISTER_EVENTFD: - case IORING_REGISTER_EVENTFD_ASYNC: ret = -EINVAL; if (nr_args != 1) break; - ret = io_eventfd_register(ctx, arg); - if (ret) + ret = io_eventfd_register(ctx, arg, 0); + break; + case IORING_REGISTER_EVENTFD_ASYNC: + ret = -EINVAL; + if (nr_args != 1) break; - if (opcode == IORING_REGISTER_EVENTFD_ASYNC) - ctx->eventfd_async = 1; - else - ctx->eventfd_async = 0; + ret = io_eventfd_register(ctx, arg, 1); break; case IORING_UNREGISTER_EVENTFD: ret = -EINVAL; -- 2.25.1