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=-8.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS 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 A7BF1C433DF for ; Wed, 19 Aug 2020 07:55:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67053207BB for ; Wed, 19 Aug 2020 07:55:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="bhDfrHCa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726435AbgHSHzc (ORCPT ); Wed, 19 Aug 2020 03:55:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726342AbgHSHza (ORCPT ); Wed, 19 Aug 2020 03:55:30 -0400 Received: from mail-qt1-x82d.google.com (mail-qt1-x82d.google.com [IPv6:2607:f8b0:4864:20::82d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FA39C061389 for ; Wed, 19 Aug 2020 00:55:30 -0700 (PDT) Received: by mail-qt1-x82d.google.com with SMTP id v22so17153393qtq.8 for ; Wed, 19 Aug 2020 00:55:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=zv/HE5z/9SmihVOWVHVy7kmaGXxIx5BbUCPhM4bmkJI=; b=bhDfrHCar4umWQC/5pQTx3cyoCspu9ddfdUY758vWp5Ex23r4+eDueDhIoN3ftPMuH BLHhoWCQneiERQyqdEVeTuaVZ8iJYsZg+cGDL7tCZAD95jVF3Ovo8YKeClCPOTevtISQ 8/6DLC6R3n8ltx9LD/iRiFsMOtLNcv6/gk55z8bnhMH6KDFLL/PTCspYJbudUjaC5NgQ f5Lt/p/YGMPN/yxQ8gTel6NYoeTu34rcv+EFuBFdlKowmBzpnaDgu8eAjF2TbKFnzook kZw9w+B7XAdWcEXrZjID5W3PZVIgSgQGxdnLOMNp7JqyLppFf8i2rG1PGpyfMYB5/9+4 GCdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zv/HE5z/9SmihVOWVHVy7kmaGXxIx5BbUCPhM4bmkJI=; b=GedSeil2TjA3PSazM5oY+167Q/E5/OsflhD783LSzKXNCLA2opLa2Zq/+3UX8FhFaq SOB9/K1W/WAKJTDEaqrvpceAni0DEDoh/0KoMzc9hPhrWDkAuVVPQpkCNBHWKaqHp4ag JhiSeVt6kh5mC8XckEfP71LF/2BsX1IsLufb2bY3LowsZM1WPxDfGwp7ZHAjbSPqQ/JA /k+7WSogaamylIRa8tASF5O059+4k7wZy/G8PBegLD32VgEZSsefQ81jlAsbTmaqd6Vr wvAiltbES1C9jBiBaMYnULf4ZhnAlmIlDTI7G5UrFl/8lQGhZzuD+gKWnorhmQ2j9ZYP Oj0Q== X-Gm-Message-State: AOAM532ZxPvsj0nQNeUJhaOBjNP6OVmawrOEtqfeMsUKWgqEmAJQT5Ij BNRPEuo9AefHJWixs2QhfURJ7OpWyPego9tll2FLU/0Cdls= X-Google-Smtp-Source: ABdhPJy9Bgm4mJXsul/r3204P9Lm1mIpLO7uyKp9aUUrnUOzEoJNBUwNEvIsVH2nNvgGGG1N3pI2t76GX06NupBU4+E= X-Received: by 2002:aed:2825:: with SMTP id r34mr20121401qtd.321.1597823729448; Wed, 19 Aug 2020 00:55:29 -0700 (PDT) MIME-Version: 1.0 References: <477c2759-19c1-1cb8-af4c-33f87f7393d7@kernel.dk> <004a0e61-80a5-cba1-0894-1331686fcd1a@kernel.dk> In-Reply-To: From: Dmitry Shulyak Date: Wed, 19 Aug 2020 10:55:18 +0300 Message-ID: Subject: Re: Very low write throughput on file opened with O_SYNC/O_DSYNC To: Jens Axboe Cc: io-uring@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org reproducer with liburing - https://github.com/dshulyak/liburing/blob/async-repro/test/async-repro.c i am using self-written library in golang for interacting with uring, but i can reproduce the same issue with that snippet consistently. On Tue, 18 Aug 2020 at 19:42, Jens Axboe wrote: > > 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 >