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 X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 13B66C2D0C2 for ; Mon, 30 Dec 2019 18:25:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA40C20722 for ; Mon, 30 Dec 2019 18:25:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="lyCpJrac" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727579AbfL3SZg (ORCPT ); Mon, 30 Dec 2019 13:25:36 -0500 Received: from mail-wr1-f67.google.com ([209.85.221.67]:43093 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727571AbfL3SZg (ORCPT ); Mon, 30 Dec 2019 13:25:36 -0500 Received: by mail-wr1-f67.google.com with SMTP id d16so33424578wre.10 for ; Mon, 30 Dec 2019 10:25:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:subject:date:message-id:in-reply-to:references:mime-version :content-transfer-encoding; bh=NdKMJR04HFIYXG4fWVw9V/B5syfQZiMOL+WyxbMF7sk=; b=lyCpJraccIfre4HhX4QGYKLAbveI5KpndIjgRKKufCz38wtsCPMeycXtq6RrT12SE+ wJ14ZMOUAdLIENOHwl66WSiZe3aRAl3LB7eUxCxgnfpUkDCsBpb9qhQTNXdMUI226gxW gzizk/2/pN9nshRkVqxHLtni0kGeKn2Qnbg/EBYvcucx26g7bjEbh36i+mDInMTaS9Wl jTKuJbmrrugmqJ5hP3DjspGNlKIvB8rCsu0LpQHncC9Hu3eMLRxaiO9Z+LGKMKEYuUGK dVxbLEoGnC92mMf18cRu5ZJjrFe+vrNjvKLIZnfjz5MmC0xYDDpJZvkx+oGAGnhJ+EVY qieQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=NdKMJR04HFIYXG4fWVw9V/B5syfQZiMOL+WyxbMF7sk=; b=N+y1CVp8gLFcAh8mlk4MA2bVJni/cPDaa6vASHpm1HGPfEESdI1QYbav6FWHRQtDtp PaKZ21XD34pHV89jzZum6zfx1ErINdBFbF+CVyuZke48F42LVXwIkzZ7jVyLbUfIKFfO ahZCUCNI9MlZ2pyBLEy5198XTJb2MSKx0bpDbtqthzNpnnAlIGrPkocSEP5QZucsEgh3 vWmx9kNaODofJxeF8jXB4ghawPMzSich441mPJyWO6zINbBUqTBDavdrYUm+F4wpJ1SM ZCWB1AOulCcshvyHYW/g1zJxOD+j5F7O44o/sdduuSROCde9THFwGRtlal4aAj2goiIg Qigg== X-Gm-Message-State: APjAAAUCtSCZhmuL9krVEIYjnjA4ZY/sNFNKOcvFle+FNC2CotXUQe9g Y0Ggj+EcjwiQ9NCOke0ttE9oUXXb X-Google-Smtp-Source: APXvYqwMwgFiEeyMC4Rza2fNSDMMYI9cv7iTb2kGI+1zI6aKNyS1i0oWsGWPL0mGHwOjYaNQmU25Aw== X-Received: by 2002:adf:e5cf:: with SMTP id a15mr50880639wrn.140.1577730334674; Mon, 30 Dec 2019 10:25:34 -0800 (PST) Received: from localhost.localdomain ([109.126.145.157]) by smtp.gmail.com with ESMTPSA id u24sm231590wml.10.2019.12.30.10.25.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 30 Dec 2019 10:25:34 -0800 (PST) From: Pavel Begunkov To: Jens Axboe , io-uring@vger.kernel.org Subject: [PATCH 3/4] io_uring: optimise commit_sqring() for common case Date: Mon, 30 Dec 2019 21:24:46 +0300 Message-Id: <5f61617ff3347304948d46c5257cc52581f527fe.1577729827.git.asml.silence@gmail.com> X-Mailer: git-send-email 2.24.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org It should be pretty rare to not submitting anything when there is something in the ring. No need to keep heuristics for this case. Signed-off-by: Pavel Begunkov --- fs/io_uring.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 05d07974a5b3..642aca3f2d1f 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4506,14 +4506,12 @@ static void io_commit_sqring(struct io_ring_ctx *ctx) { struct io_rings *rings = ctx->rings; - if (ctx->cached_sq_head != READ_ONCE(rings->sq.head)) { - /* - * Ensure any loads from the SQEs are done at this point, - * since once we write the new head, the application could - * write new data to them. - */ - smp_store_release(&rings->sq.head, ctx->cached_sq_head); - } + /* + * Ensure any loads from the SQEs are done at this point, + * since once we write the new head, the application could + * write new data to them. + */ + smp_store_release(&rings->sq.head, ctx->cached_sq_head); } /* -- 2.24.0