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 D3B91C433F5 for ; Wed, 23 Mar 2022 12:29:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241269AbiCWMbF (ORCPT ); Wed, 23 Mar 2022 08:31:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37108 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231716AbiCWMbF (ORCPT ); Wed, 23 Mar 2022 08:31:05 -0400 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E3544839F for ; Wed, 23 Mar 2022 05:29:36 -0700 (PDT) Received: by mail-pg1-x531.google.com with SMTP id o13so972350pgc.12 for ; Wed, 23 Mar 2022 05:29:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20210112.gappssmtp.com; s=20210112; h=from:to:in-reply-to:references:subject:message-id:date:mime-version :content-transfer-encoding; bh=AR6y2GpmspFEQuz6jvd6wROyZhk41z7w9g201D/IBhk=; b=DQrUnR9RLmSnDoZKi8e0jVpp1Kn/21dsZzmIpimBsYT9dnAwnLqLNtitk+omyT8Sy+ JCM6edTfUQlHG+lIitD7xJaVIh3xNyhUs0/mOeK5g+UgdM/FLDwtEsW+k1/5F9YrhNXU wAiklUmQEExb0dTJH3JbDbDrQ9SjDyjUB7whDBdHUVqLxbO2+Fd6L7i7q85F1HnWjj5u axsGIJP49JCjnSIw5fJ/VEfZBxv/aemzI1UfF+03uvWAruTSTDtagQQlufLU3yjzLWe1 Hzju3ry+sE8921CtZim8eT/oiw8UtR8YqENTkB9J0K+nHm+LFQm9wNUPXKDyGty6imHp bmAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:in-reply-to:references:subject :message-id:date:mime-version:content-transfer-encoding; bh=AR6y2GpmspFEQuz6jvd6wROyZhk41z7w9g201D/IBhk=; b=zyvVpXRkZidPDFrG0Z3Yg2eAyoge773xA3GbWTOUEBskl7yCzi1iTB78v3WxHZ0tOo 67DaPszoTm3PqbwXr0F0aMydbOFLKH64K0GpMooz0rT77p8kizCObC11bUZQjFOu1Ea+ QuLgcXAFgwKJ3YbQfiCp7uIMqVuiIXWGPnWO1K37Ai9uog92jXFGihPfo1yNnceQeU0O 1blOYUwM7JXK2Y0QMUUaRHW5CUXsxzqQzvfaLKWvIaLnAIAotHNMeBKhahIO8g59Ptco nW3T/MFrJitFtRNwjz1cJ93A5HNNbpRIJxlZk1r4jlYlW4UYyG9ulndwp3Oz1U2S3+wG B3Jw== X-Gm-Message-State: AOAM533Hn52FpxIJOz2euZ5h4BLVapxzaITIrEL7aGyzAKeu6WzREObT 1fBHid2DWvDYeviwuc2tE5+4TWk5vLqtpEHD X-Google-Smtp-Source: ABdhPJyZxPiffaY9YuD9aHm6jgqg0Mt2Syaon1DrDnjM/jHvwpaa5x0iREBaiMlSV32UIZIYqKyJhw== X-Received: by 2002:a63:801:0:b0:382:a089:59d3 with SMTP id 1-20020a630801000000b00382a08959d3mr8970411pgi.350.1648038575655; Wed, 23 Mar 2022 05:29:35 -0700 (PDT) Received: from [127.0.1.1] ([198.8.77.157]) by smtp.gmail.com with ESMTPSA id c21-20020a637255000000b003822e80f132sm14252121pgn.12.2022.03.23.05.29.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Mar 2022 05:29:35 -0700 (PDT) From: Jens Axboe To: io-uring@vger.kernel.org, Pavel Begunkov In-Reply-To: References: Subject: Re: [PATCH 0/3] optimise submit+iopoll mutex locking Message-Id: <164803857464.12296.859321851786945843.b4-ty@kernel.dk> Date: Wed, 23 Mar 2022 06:29:34 -0600 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Tue, 22 Mar 2022 14:07:55 +0000, Pavel Begunkov wrote: > This saves one mutex lock/unlock pair per syscall when users do > submit + getevents. Perf tells that for QD1 iopoll this patch reduces overhead > on locking from ~4.3% to ~2.6%, iow cuts 1.3% - 1.9% of CPU time. Something > similar I see in final throughput. > > It's a good win for smaller QD, especially considering that io_uring only > takes about 20-30% of all cycles, the rest goes to syscalling, the block > layer and below. > > [...] Applied, thanks! [1/3] io_uring: split off IOPOLL argument verifiction (no commit info) [2/3] io_uring: pre-calculate syscall iopolling decision (no commit info) [3/3] io_uring: optimise mutex locking for submit+iopoll (no commit info) Best regards, -- Jens Axboe