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=-12.5 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,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 D9110C433E1 for ; Mon, 24 Aug 2020 14:06:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AE6ED206B5 for ; Mon, 24 Aug 2020 14:06:54 +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="wZ+dWXBr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725890AbgHXOGy (ORCPT ); Mon, 24 Aug 2020 10:06:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58492 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725780AbgHXOGs (ORCPT ); Mon, 24 Aug 2020 10:06:48 -0400 Received: from mail-io1-xd2b.google.com (mail-io1-xd2b.google.com [IPv6:2607:f8b0:4864:20::d2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7AF8C061573 for ; Mon, 24 Aug 2020 07:06:48 -0700 (PDT) Received: by mail-io1-xd2b.google.com with SMTP id s1so8738033iot.10 for ; Mon, 24 Aug 2020 07:06:48 -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=Ua76pblU+7nsDLQxC3/2lfZ03EpaZdfkBHXJQNE0zLQ=; b=wZ+dWXBr0/PHMTaR22VJ0tgK7JfW+2iFS4yQxp0qrOsp0FjgtB35dFG92Qv1D1Yil5 UJiZG/wl5sAlx6UJyFwgm/ugTQmGsntEUqH51XhO4lCdEf8NhLgJAMYNdR1+mWqZsFZS G1pw3esqZK/Jzuq9ECo5NoJp+FrTxabQScId1/aE88vsMRjYU/+yu5mqgN43rEgRYqPR Kfrn1DdPbqDXY/fsLjEWYRcBmPGecHdJk7c5byJAyp/Rp9OhkD6Wl6w+avRIW378cotE 4bI2nIGEsSK+/VWQeYGjoxVhY6wVJylQqwZpxeCMtvUXd7rBpQ8609yFuCqSVeAqEXbR HxDw== 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=Ua76pblU+7nsDLQxC3/2lfZ03EpaZdfkBHXJQNE0zLQ=; b=DQVpM+2+9RacU0mnrNihh+RD/7ifsDk6S+ieNDmpImh9uc6nuZ07bcJKpHdZ1FbbFN T//YmNhSRg4MWibFcLElIQaX8UJL9lMj84+feI4wEW1jwkiy4s0vp/oB1bQEwsoS5z+L Q1tcnJQhAmxBZgQ5UqM8OCxoI6mCJaXMey3clX7W7QVycRCw/klb5qUXqvRp8Jwm1CWO PSdCmtiJKkUaM/qW4T5RCy7bCtaXKlS4/J0tFvWmuptz66IeK+K0cDRDyj5DeLcHMwvP QpY/+O8mw6HVnbZ1rOYmQRIIpPUDOMSRGuHHvaYpChSXcSaKEAANd2KojTWepmQimuVw bwVw== X-Gm-Message-State: AOAM533PistMvOj5goWjIcadeeCqx472cqXnOvVyqRk5JyGOoFgGGNiM 1O3qwLHBJBBqZDqXbCiSwf345hwN7y3hZF8O X-Google-Smtp-Source: ABdhPJwISmvrmVTROwfA+S7OtX9+L0L8xMkj9GGbiLxHWyWDYR3y54qDe8uFQjZVYrea7rDZRDK8mQ== X-Received: by 2002:a6b:e517:: with SMTP id y23mr4971430ioc.190.1598278005329; Mon, 24 Aug 2020 07:06:45 -0700 (PDT) Received: from [192.168.1.58] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id h7sm7283275ilo.51.2020.08.24.07.06.44 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 24 Aug 2020 07:06:44 -0700 (PDT) Subject: Re: Large number of empty reads on 5.9-rc2 under moderate load To: Dmitry Shulyak Cc: io-uring@vger.kernel.org References: <7a148c5e-4403-9c8e-cc08-98cd552a7322@kernel.dk> From: Jens Axboe Message-ID: <06d07d6c-3e91-b2a7-7e03-f6390e787085@kernel.dk> Date: Mon, 24 Aug 2020 08:06:43 -0600 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 8/24/20 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 -- Jens Axboe