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=-8.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A63CBC433E1 for ; Tue, 18 Aug 2020 16:42:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7FC5C20658 for ; Tue, 18 Aug 2020 16:42:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="HDC8JxZJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726806AbgHRQmZ (ORCPT ); Tue, 18 Aug 2020 12:42:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44730 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726721AbgHRQmW (ORCPT ); Tue, 18 Aug 2020 12:42:22 -0400 Received: from mail-pl1-x634.google.com (mail-pl1-x634.google.com [IPv6:2607:f8b0:4864:20::634]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81AF3C061389 for ; Tue, 18 Aug 2020 09:42:22 -0700 (PDT) Received: by mail-pl1-x634.google.com with SMTP id bh1so9463284plb.12 for ; Tue, 18 Aug 2020 09:42:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=jwDiGVsm+D4sTPvo7BwI/U+2xiBy0UHOPd3WZFDXMoA=; b=HDC8JxZJokWZogTYBmRnUn1Cz05XHvvF9x+rUsVrw0yimX7LuCoWVTQ3JK3xnA29TN BPdw4/zrgZw12eMEyDnPvM0Wd5wdxzMS14ofeYyEriqhFZZa/wm2RnVgA5X/hMfT44v7 Xwy7j62qO+MtZmJoErNQfWeOAP2o9rNifhgXiE5323VMShaJTAVoHmBdB2I8NqqLFRsk p0YrrpIRvnAE8YUtK3Q/2FIs0olSSYHA+syn1ZKStkTE+kqkc6QiIMiSvimjyyibUXCA 6rdZwED5mTipBMYhoRnhCPsI+3FB2CSIvfq2IHKxRNF/qo4YPP2r4ZbyhTwMJYlK6Z/+ juoQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=jwDiGVsm+D4sTPvo7BwI/U+2xiBy0UHOPd3WZFDXMoA=; b=aAEjXcQPyG/SENBq8Sj/rTq/xwnShsHOiV51Uk0XjE7AxWJIc2z7us1odQwZHkrw37 zNbvtd7skXTWXZHYqlOhndtXjhoFTBNRinwR8VVaQ+GMfgLZfxCBmpsjeygzTkrzuoZ8 68Jj3RgIpZqz+x2gvwwQ/xgNvYHxr4XFKwO7DtWXlRG9/VAGqFUYvGW88xQbvgj+MpUk YOMwSpX3LgKBrc5L8k4ZVLPaVUmhxrQZDR7aLb8FUkZdANGH91+Ncsb8W3ooD4bfInEl tcwBeb2QZRVGO3mw8G0rvfgdytcqgGTpcZtgZWHhLkfez/F3707OoX9FLuxbp32QlfWY w7dw== X-Gm-Message-State: AOAM531pNBj5biuwdTWwIhRc7MbgbX662LgwlyXtyQyQc87na1DwrOub 1Nf/WwNj96+tWzHPhzzCh3dWKJfBw+0BBIU9 X-Google-Smtp-Source: ABdhPJywCyYj6/SxFQwJayus5bQ50Hpc/U0TRarak9YRZwkRut5jXaGfJ4RyQN4zkdBU0xbPgrXn6g== X-Received: by 2002:a17:90a:ce94:: with SMTP id g20mr621133pju.61.1597768939651; Tue, 18 Aug 2020 09:42:19 -0700 (PDT) Received: from ?IPv6:2605:e000:100e:8c61:9214:36a5:5cec:a06d? ([2605:e000:100e:8c61:9214:36a5:5cec:a06d]) by smtp.gmail.com with ESMTPSA id s17sm15312878pgm.63.2020.08.18.09.42.18 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Aug 2020 09:42:19 -0700 (PDT) Subject: Re: Very low write throughput on file opened with O_SYNC/O_DSYNC To: Dmitry Shulyak Cc: io-uring@vger.kernel.org References: <477c2759-19c1-1cb8-af4c-33f87f7393d7@kernel.dk> <004a0e61-80a5-cba1-0894-1331686fcd1a@kernel.dk> From: Jens Axboe Message-ID: Date: Tue, 18 Aug 2020 09:42:17 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 8/18/20 9:09 AM, Dmitry Shulyak wrote: > it worked, but there are some issues. > with o_dsync and even moderate submission rate threads are stuck in > some cpu task (99.9% cpu consumption), and make very slow progress. > have you expected it? it must be something specific to uring, i can't > reproduce this condition by writing from 2048 threads. Do you have a reproducer I can run? Curious what that CPU spin is, that obviously shouldn't happen. -- Jens Axboe