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 38371C433FE for ; Thu, 3 Feb 2022 23:34:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356024AbiBCXer (ORCPT ); Thu, 3 Feb 2022 18:34:47 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43554 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356008AbiBCXer (ORCPT ); Thu, 3 Feb 2022 18:34:47 -0500 Received: from mail-wr1-x430.google.com (mail-wr1-x430.google.com [IPv6:2a00:1450:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5916BC06173D for ; Thu, 3 Feb 2022 15:34:46 -0800 (PST) Received: by mail-wr1-x430.google.com with SMTP id u15so8073292wrt.3 for ; Thu, 03 Feb 2022 15:34:46 -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=H/qApFabyCqynxzYsW+8dYD6QrjWQhPeK69O6kd4Euc=; b=6s9JhcKBntjBkKFlGZfvX6NL1mxXzuU5vbBiVSaI9+eNj6JbcfL4wbiHwme+u88Yn6 7b6goefqeUoqW917umdzcCP1sZUr2feWA36MqnrrLwtGbj76zU/P8WaB2wzY/hhrVXSC i5uFEyyvxFraNoC09AgegOVXhamcvWME8EgZQtfghNTgJOEKax+VzEaVds7OB1AWF1Yo tR3sNc++6aVtAArxqIU23GVYpS5wxWOzhZEJT9NkZMOhg/aXDSHuvAR2Zr7zIDMb7kCK grWgzRvkt4OmkLkKmMwZ5AErndsqfHQznFEzxf1QmJ5vs9KYDLJRMiWnmNV6vptd94EL WZJA== 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=H/qApFabyCqynxzYsW+8dYD6QrjWQhPeK69O6kd4Euc=; b=HFwtMjo0rwqGdWaVQibBCr5YBYefP1UE27XvrbQ2yW/TFIAlcVbxJE8lR9rJb6/wW5 1M0ne6NT4OG6PkNuHIaKMMJiPMUOR6FF4hcl9xMgPsnYRuwTpfvUyRc4HRr0kK8qWmKC ej2bWyZOMQzMJvQSbgR1VS3rwhAPPes45lgiFdRm+gCCuDCfx2RcbS/ht5/1dX+ja5LQ JCMKaPlxMYp4lxORPrbOUESyv0UHHpX5gNY6hri/34pKMFbjxvud/ccSCoMzUswGYBPI icwDl5loKQl5AlEN7TBSxdbA9e5REWXpbudhNCrq44Ounq+4GF0Vysu4r/jdaHY8K17l S9cg== X-Gm-Message-State: AOAM530Q3N0IDPHmS9VlLy1Ny6yiv/TbQWrREW0TqJyznELgrJx5q/hX Ek2Y4EKxWHQWmwLeLDDNP5rEVfOSbhzNoQ== X-Google-Smtp-Source: ABdhPJx9B33DIul/jfnrSTzI4eCfy8T6j/MuusQGZtwW2rmZBbRbowZ88NOkXNJHe3FO4BqUYybjkg== X-Received: by 2002:a5d:55c3:: with SMTP id i3mr220314wrw.250.1643931284877; Thu, 03 Feb 2022 15:34:44 -0800 (PST) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6d:f804:0:28c2:5854:c832:e580]) by smtp.gmail.com with ESMTPSA id j15sm148494wmq.19.2022.02.03.15.34.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Feb 2022 15:34:44 -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 v5 3/4] io_uring: avoid ring quiesce for IORING_REGISTER_EVENTFD_ASYNC Date: Thu, 3 Feb 2022 23:34:38 +0000 Message-Id: <20220203233439.845408-4-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220203233439.845408-1-usama.arif@bytedance.com> References: <20220203233439.845408-1-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 51602bddb9a8..5ae51ea12f0f 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; bool unregistering; }; @@ -342,7 +343,6 @@ 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; @@ -1756,7 +1756,7 @@ 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: @@ -9377,7 +9377,8 @@ 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; @@ -9416,6 +9417,7 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg) } ev_fd->ctx = ctx; ev_fd->unregistering = false; + ev_fd->eventfd_async = eventfd_async; rcu_assign_pointer(ctx->io_ev_fd, ev_fd); ret = 0; @@ -11029,6 +11031,7 @@ 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: @@ -11129,17 +11132,16 @@ 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