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=-3.6 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,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 3C0CEC433E1 for ; Tue, 25 Aug 2020 14:15:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1570620665 for ; Tue, 25 Aug 2020 14:15:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EUATDmAB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725998AbgHYOPP (ORCPT ); Tue, 25 Aug 2020 10:15:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725893AbgHYOPM (ORCPT ); Tue, 25 Aug 2020 10:15:12 -0400 Received: from mail-qk1-x741.google.com (mail-qk1-x741.google.com [IPv6:2607:f8b0:4864:20::741]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 34CC1C061574 for ; Tue, 25 Aug 2020 07:15:12 -0700 (PDT) Received: by mail-qk1-x741.google.com with SMTP id p25so11036009qkp.2 for ; Tue, 25 Aug 2020 07:15:12 -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=+q/Y9Z8M5jFm+p3bIMgmS4dOLk/L3b5vpQ1zNJvOTzw=; b=EUATDmABSbnXL+6hswKIjlsT1ssOEMg3CwgUwdawDJ6Gf+Xpidqfvg2SJUSRu8JIRw /GGyzhojsFYiDOO1YXKf3iBHyPNQQo2bvNHj/dC4fiIUw0x8QIeinw4jhBPW6myHsJpl AwED1TJsaC3b33dhlUyJvIbIx4YCOBAEUcSKC+1dRpXK1QxEFc8utISr18YpkJ5xTjpa Ka8pMBaNTHTGc0dE3hyR9KBFLlX2/+/6rG+y8ckmzlZRaIf4rTxnk10rwsBpaYhkQZPK 8vkfE1FdZLuUBzbF4aXxwf+nKfPCg2EYOx57XjSMTEhgcKkwPIgqDMO5TbDEqbOhfe7j dggA== 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=+q/Y9Z8M5jFm+p3bIMgmS4dOLk/L3b5vpQ1zNJvOTzw=; b=s9NqIrhNGMJcJtlvJusevmCrq7q88u7sX0PeK/UGSwbHDcKKWDniCChm1LfE+2KZ9Z bxk/7shrWfSnppA0PZAyuU4Z6GBxibdki3jJs2b228BDTGTVfPLyZ+WngYDAAEVIKptY bBB12b7lbKgsxDAsPXWkjGFwDg7cFl0WLN7D0VYvH+2w/cmYcyRP5scJXaWmq5kgAixG CtxFmcx0/d2pYcfhxgm3DO+jqT9BC7l3r8SDc+1RT1cO3XFhoUOWqJstTlHGE06vM59L wtu8A62vhTETw/VZJeehzJd36WiuphbEclyAUbPTA3TdC4RcrVTdGOI0+rcDU6pWFqEW NPTg== X-Gm-Message-State: AOAM532PoeawkMQ7Ap0xOzKaIqV330/ZPVWsGjmb+vjyXaZSg5F0VLg8 uri7erG7h4tlECETrQ2+yBoQb0tPFl1ha6b6qaA= X-Google-Smtp-Source: ABdhPJyazhVkJAkU6MpSPsSKooedaROm+eB9g1+mPl1ms4qlB5EeSWPSSc/xAEJJdSxYkx0sSF9oV8QdloIq31Ex55Y= X-Received: by 2002:a05:620a:1495:: with SMTP id w21mr1660975qkj.499.1598364909166; Tue, 25 Aug 2020 07:15:09 -0700 (PDT) MIME-Version: 1.0 References: <7a148c5e-4403-9c8e-cc08-98cd552a7322@kernel.dk> <06d07d6c-3e91-b2a7-7e03-f6390e787085@kernel.dk> <282f1b86-0cf3-dd8d-911f-813d3db44352@kernel.dk> <42573664-450d-bfe4-aa96-ca1ae0704adb@kernel.dk> <8076e289-2e0b-5676-aaac-eff94245a298@kernel.dk> In-Reply-To: <8076e289-2e0b-5676-aaac-eff94245a298@kernel.dk> From: Dmitry Shulyak Date: Tue, 25 Aug 2020 17:14:57 +0300 Message-ID: Subject: Re: Large number of empty reads on 5.9-rc2 under moderate load 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 I was doing readv with the same tool that i shared earlier: go test ./fs -run=xx -bench=BenchmarkReadAt/os_5 -benchtime=8000000x -cpu=256 On 5.8.3 it is consistently > 100 mb/s, on 5.9-rc2 ~50 mb/s on my device. with uring i was getting > 250 mb/s, and now ~70 mb/s. double checked if there is any difference with writev, and i don't see any. On Tue, 25 Aug 2020 at 16:39, Jens Axboe wrote: > > On 8/25/20 2:52 AM, Dmitry Shulyak wrote: > > this patch fixes the issue with 0 reads. there seems to be a > > regression that is not specific to uring, > > regular syscall reads slowed down noticeably. > > Do you have a test case? Related to specific system calls, or just > overall? My initial suspicion would be Yet Another one of the > security fixes... > > -- > Jens Axboe >