From patchwork Tue Jan 3 03:04:02 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Begunkov X-Patchwork-Id: 13087126 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 C236CC54EBD for ; Tue, 3 Jan 2023 03:05:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236631AbjACDFf (ORCPT ); Mon, 2 Jan 2023 22:05:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43684 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236625AbjACDFa (ORCPT ); Mon, 2 Jan 2023 22:05:30 -0500 Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [IPv6:2a00:1450:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 88F56BF5F for ; Mon, 2 Jan 2023 19:05:29 -0800 (PST) Received: by mail-wm1-x32d.google.com with SMTP id k22-20020a05600c1c9600b003d1ee3a6289so22169831wms.2 for ; Mon, 02 Jan 2023 19:05:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=MoTHAaXqKBt52ZvHVgZSMQyuUe+Z8C2Fhn5NtXMvC9E=; b=mm5r2qFhbJcOlDXjGU+IglpBpoWiPA1/gsJKN4EB9iVSwi5y89uhdlDvWVNZZVGMkx WJpRjLphpUvmF6IuHeOpLDEDRalW+9NA7331XlkhrWPGMj75OanjHjSznNpdVPUf6d1G +z9YZRBnydcpJ8q3gsiDMopB5GphQ89zuswTW9dFX2tkQrJTpAKsIXOnxmOOjUXRmA88 FqlQdeaVav9xJyX4M7zEr1sk56GRFNtTefMBbaS26Md0EG9WulAETfpvAd6OS+15lIB7 wusQiIudNcpdPL6Jzqt1hGYd/u2YE80yIE6bblcn1cV+ksKJaC40ST0K8XcWRfV0tsEW aarA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=MoTHAaXqKBt52ZvHVgZSMQyuUe+Z8C2Fhn5NtXMvC9E=; b=sDOV0VOB1nVfyYcph1YPvMzQdhQZM3gs7Q6U20mXOIlN0sWe9g61MvFw5LoankIewK j7QfFqN/9kICV96HnafJMvn/eCXTa+RFvrgelBtk7rk5RCZxbnsd71eQB/4HUvxfdfsW KJ2uuyXtI52XBB0nRTmcpPeWe0OqL5JWJDIgzW8m+oifzn9DwOEp/aJ/7HbIeee1z2sr hp16c7xYZWNBBoZLMHEa7FE24zG67Sr303NQP/U59kBFuTm1lVIj0Vq8tV+2QUzcLYag YhaqnKr9SalymJ2sxhpJVRqPbMRW1hOTHg2/ZHmYRMb7C0X6Hy+J5byaJrtbhLHHDX6W qFcA== X-Gm-Message-State: AFqh2ko8dNxOZ06D7nvBevpb3k+g2WVFWLuewa+prbziVNRmtuRXWjmA GTj662YFf/iSoIET3GNv9woz4QPpzjc= X-Google-Smtp-Source: AMrXdXv8/sKjyIRjsipPHhnNj8YicQz5CvOVA1qBeYsUPAKl+saptt3rhESiHbYNmgc1F4e6NKvRoA== X-Received: by 2002:a05:600c:3b82:b0:3d3:4877:e560 with SMTP id n2-20020a05600c3b8200b003d34877e560mr29520586wms.27.1672715127914; Mon, 02 Jan 2023 19:05:27 -0800 (PST) Received: from 127.0.0.1localhost (188.28.229.101.threembb.co.uk. [188.28.229.101]) by smtp.gmail.com with ESMTPSA id m1-20020a7bca41000000b003d1de805de5sm39967839wml.16.2023.01.02.19.05.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 02 Jan 2023 19:05:27 -0800 (PST) From: Pavel Begunkov To: io-uring@vger.kernel.org Cc: Jens Axboe , asml.silence@gmail.com Subject: [RFC v2 11/13] io_uring: wake up optimisations Date: Tue, 3 Jan 2023 03:04:02 +0000 Message-Id: <1b09f9674e9140ef9623c5a26ab7b826d4d4fe69.1672713341.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Flush completions is done either from the submit syscall or by the task_work, both are in the context of the submitter task, and when it goes for a single threaded rings like implied by ->task_complete, there won't be any waiters on ->cq_wait but the master task. That means that there can be no tasks sleeping on cq_wait while we run __io_submit_flush_completions() and so waking up can be skipped. Signed-off-by: Pavel Begunkov --- io_uring/io_uring.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index d2a3d9928ba3..98d0d9e49be0 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -621,6 +621,25 @@ static inline void __io_cq_unlock_post(struct io_ring_ctx *ctx) io_cqring_wake(ctx); } +static inline void __io_cq_unlock_post_flush(struct io_ring_ctx *ctx) + __releases(ctx->completion_lock) +{ + io_commit_cqring(ctx); + __io_cq_unlock(ctx); + io_commit_cqring_flush(ctx); + + /* + * As ->task_complete implies that the ring is single tasked, cq_wait + * may only be waited on by the current in io_cqring_wait(), but since + * it will re-check the wakeup conditions once we return we can safely + * skip waking it up. + */ + if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN)) { + smp_mb(); + __io_cqring_wake(ctx); + } +} + void io_cq_unlock_post(struct io_ring_ctx *ctx) __releases(ctx->completion_lock) { @@ -1461,7 +1480,7 @@ static void __io_submit_flush_completions(struct io_ring_ctx *ctx) } } } - __io_cq_unlock_post(ctx); + __io_cq_unlock_post_flush(ctx); if (!wq_list_empty(&ctx->submit_state.compl_reqs)) { io_free_batch_list(ctx, state->compl_reqs.first);