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 0FAD5C433E1 for ; Mon, 24 Aug 2020 15:33:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E38532078D for ; Mon, 24 Aug 2020 15:33:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="eheV2p2O" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727979AbgHXPdV (ORCPT ); Mon, 24 Aug 2020 11:33:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43836 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725973AbgHXPdQ (ORCPT ); Mon, 24 Aug 2020 11:33:16 -0400 Received: from mail-qv1-xf41.google.com (mail-qv1-xf41.google.com [IPv6:2607:f8b0:4864:20::f41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93ED3C061573 for ; Mon, 24 Aug 2020 08:33:15 -0700 (PDT) Received: by mail-qv1-xf41.google.com with SMTP id b2so3897849qvp.9 for ; Mon, 24 Aug 2020 08:33:15 -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=GobpPjdLg/JWnf3d+r1qbat1a2WxvEb1wGe1Mt+LEB0=; b=eheV2p2Oi8NOI++Zg6Qhoxdpb8Dr+/ih3UsgBtyj0GhJk6pwG+0fL2JbXEQTi00epb bjY04aJKX2mAzSuMjJe1QBHcZkCC+SFxLEEOSftUN3Kqoz7r80tK6k0pCkeu14p8iKCp OHLCuPiFVkjzYmYLsIPFx7S7H39aXLHS0TfEoEw+RnIziMXUC3d8nXfkHXsm2p3Eo4BH iPeEtcDEn7Ya4Y2QFGMbrJYSu2dYd7zN6IPRYIMpV+K8W+OqGQnnO+p6D/gy5VCbLG8/ q4vjBINYK9Qtlk0zWyMCKr4+/Ez483lhTEf/p9Ukxoo8kSTBC/whkL0LWrapkpEWNaul 8Q3Q== 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=GobpPjdLg/JWnf3d+r1qbat1a2WxvEb1wGe1Mt+LEB0=; b=g3sAKlBafHhr76X0GDIwEJe3zOggR+8L5Y8LX6KjU2howazZ9Onc0ahZd3iHt2Ktvu +Vt+CvEHUyGk5jFTG4wbF947DfYIJforGidPcn9V57VB3Hfb59XfPumyyiQigY2bw/J4 K6WkZEIWqqnK5jdtHaHZGK3A38/Jig+0w/843RryKj8xf+R0SheQui9UW7jNJqCFz21z InmOSNQExPYaDyj/tHS6fGvfKHkQHCGBAH2MvuDjFAZ0ADTvsf3g1KiiqS8eWhqWFQ+/ 4FFtyjfboV+y4vH4DOTFkbRPEXeCB0571TnDIrg8VwDuaofJehF+GZa07THESARBcIZG PtYQ== X-Gm-Message-State: AOAM533Vr8QxjE2+1rV8MXjWWp9kkQTHcFJmjr8U8LY3924felYOmznl Cn+ewJRDdblUU4DfXtXi2pdpJRZ4LEwxi8HmaBbF9Rh5Hjw= X-Google-Smtp-Source: ABdhPJzk4A8mxlJ7fQG+mfC79HmnF8ubSwdiy3VwfS6SCkgh+35ptej+DyFBTGxzHLgsKnkvF9IQ/V46oMv1wk+2NcE= X-Received: by 2002:a0c:f9cd:: with SMTP id j13mr5272651qvo.227.1598283193693; Mon, 24 Aug 2020 08:33:13 -0700 (PDT) MIME-Version: 1.0 References: <7a148c5e-4403-9c8e-cc08-98cd552a7322@kernel.dk> <06d07d6c-3e91-b2a7-7e03-f6390e787085@kernel.dk> In-Reply-To: From: Dmitry Shulyak Date: Mon, 24 Aug 2020 18:33:02 +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 Was going to look into this. I am getting 0 reads. This is on some old kingston ssd, ext4. On Mon, 24 Aug 2020 at 17:45, Jens Axboe wrote: > > On 8/24/20 8:06 AM, Jens Axboe wrote: > > On 8/24/20 5:09 AM, Dmitry Shulyak wrote: > >> library that i am using https://github.com/dshulyak/uring > >> It requires golang 1.14, if installed, benchmark can be run with: > >> go test ./fs -run=xx -bench=BenchmarkReadAt/uring_8 -benchtime=1000000x > >> go test ./fs -run=xx -bench=BenchmarkReadAt/uring_5 -benchtime=8000000x > >> > >> note that it will setup uring instance per cpu, with shared worker pool. > >> it will take me too much time to implement repro in c, but in general > >> i am simply submitting multiple concurrent > >> read requests and watching read rate. > > > > I'm fine with trying your Go version, but I can into a bit of trouble: > > > > axboe@amd ~/g/go-uring (master)> > > go test ./fs -run=xx -bench=BenchmarkReadAt/uring_8 -benchtime=1000000x > > # github.com/dshulyak/uring/fixed > > fixed/allocator.go:38:48: error: incompatible type for field 2 in struct construction (cannot use type uint64 as type syscall.Iovec_len_t) > > 38 | iovec := []syscall.Iovec{{Base: &mem[0], Len: uint64(size)}} > > | ^ > > FAIL github.com/dshulyak/uring/fs [build failed] > > FAIL > > axboe@amd ~/g/go-uring (master)> go version > > go version go1.14.6 gccgo (Ubuntu 10.2.0-5ubuntu1~20.04) 10.2.0 linux/amd64 > > Alright, got it working. What device are you running this on? And am I > correct in assuming you get short reads, or rather 0 reads? What file > system? > > -- > Jens Axboe >