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 2773FC433F5 for ; Fri, 4 Feb 2022 14:51:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359479AbiBDOv1 (ORCPT ); Fri, 4 Feb 2022 09:51:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52206 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1359476AbiBDOv0 (ORCPT ); Fri, 4 Feb 2022 09:51:26 -0500 Received: from mail-wr1-x434.google.com (mail-wr1-x434.google.com [IPv6:2a00:1450:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C78C7C061741 for ; Fri, 4 Feb 2022 06:51:25 -0800 (PST) Received: by mail-wr1-x434.google.com with SMTP id r17so2750484wrr.6 for ; Fri, 04 Feb 2022 06:51:25 -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=5zc8mYGQQbklzCfEPq5ixDqvUH1Mr0RGq4NsmzowtCU=; b=q7cQX7sIPSRmOALm6TBpWQ/mo+y2c7GlrThj3wILGB7n2WzpXU+8SZremYwVxzsGij G4wbfSz+fec2keuXRmpWplZXoU2vxrq6jPyHhQLVAKWuAerYySuGY+3DyvIwOas7Xxue bJt0BgDjxeDxViSaqlitN225zUj03fM9SAae8IDkFXjvPYwTDeqRr08cjukhfdroSDZy MIh8Ofdt5LlhPny7r6Yji8K9glZwtL4zPbnuq/CRld5WZCybRx60kBazZ5temZpPbccT MSr3bITJgpVF3sBCebcZE9muZSJvPqrswt/BPmf/n+NEwCoaCnzY+UXCiCudufpnOyC2 49tQ== 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=5zc8mYGQQbklzCfEPq5ixDqvUH1Mr0RGq4NsmzowtCU=; b=uurmXEv0uu22eLQSJ0dLwVgJoPmIilu5WOtgaHvBtGG/Y4VTILQfML5mhONfIWAu0l NxfhBOD/MQa9NMPqb80SrkWHZrgqq4CQ0hlifyAUiWHbm22JTqD8/qxTDR8P3rzQ9oOQ j+56xYof8XtSPud10gZfS0zNSq3r1JtBSgD4B5xvWvKw5KNLj/0fQRgnp4qZHha4qNzf Vw6tSXL6DUGzpTN1qY+9jpQd3PJLA4dGIptRefgMePZaMrI4tqoX5QCKTtTpmF2T1h5d X1OM4+7/GoNLEpfnHHqTx+pZPr87ZFxwBB4L34Ki5G0pxlXDz0NwAE7eeWOtTKfCk2Ur kDaw== X-Gm-Message-State: AOAM5309r0UEPHZRwPDRl3sQA9G2yRacoxkl4rgHN2lUo+RExz5gQOQc Kl1XEj7PILvRh0mSCJTD4eLDbGfFkZB+EA== X-Google-Smtp-Source: ABdhPJz3r/hgUNyu1JFddlat0A+D16hlkSO3MwsYWonb403K1rS4BB2N+fCYnF6gfCI/1pQ27pBarA== X-Received: by 2002:a5d:4cc7:: with SMTP id c7mr2656075wrt.233.1643986284356; Fri, 04 Feb 2022 06:51:24 -0800 (PST) Received: from usaari01.cust.communityfibre.co.uk ([2a02:6b6d:f804:0:e94c:d0f2:1084:a0d3]) by smtp.gmail.com with ESMTPSA id c11sm2552898wri.43.2022.02.04.06.51.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Feb 2022 06:51:24 -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 v6 3/5] io_uring: avoid ring quiesce while registering async eventfd Date: Fri, 4 Feb 2022 14:51:15 +0000 Message-Id: <20220204145117.1186568-4-usama.arif@bytedance.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220204145117.1186568-1-usama.arif@bytedance.com> References: <20220204145117.1186568-1-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. The place where eventfd_async is read 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 ad6361aeaca7..671c57f9c1fa 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -328,6 +328,7 @@ struct io_submit_state { struct io_ev_fd { struct eventfd_ctx *cq_ev_fd; + unsigned int eventfd_async: 1; struct rcu_head rcu; }; @@ -340,7 +341,6 @@ 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; @@ -1752,7 +1752,7 @@ 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: @@ -9373,7 +9373,8 @@ 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; @@ -9396,6 +9397,7 @@ static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg) kfree(ev_fd); return ret; } + ev_fd->eventfd_async = eventfd_async; rcu_assign_pointer(ctx->io_ev_fd, ev_fd); return ret; @@ -11000,6 +11002,7 @@ 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: @@ -11100,17 +11103,16 @@ 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