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=-3.8 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 4F6E2C433EA for ; Tue, 14 Jul 2020 11:56:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2986122225 for ; Tue, 14 Jul 2020 11:56:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="BWruN3AF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728086AbgGNL4I (ORCPT ); Tue, 14 Jul 2020 07:56:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727839AbgGNL4D (ORCPT ); Tue, 14 Jul 2020 07:56:03 -0400 Received: from mail-ed1-x544.google.com (mail-ed1-x544.google.com [IPv6:2a00:1450:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24396C08C5DD for ; Tue, 14 Jul 2020 04:56:03 -0700 (PDT) Received: by mail-ed1-x544.google.com with SMTP id dg28so16747935edb.3 for ; Tue, 14 Jul 2020 04:56:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=+sjMIjM2/JFepdRAXpOHb7ghC5LhQeVZQ0Kayo5azeY=; b=BWruN3AFlA46ZLoJRaXr2SIqdS24ok0rzjPKi9syKMhMKh0JxzioNs8EdhKj+fmaW8 LtFlAX3lpklg05W9WQ2EZYCE821vzWc7x2++w2jVILwn2boWbSBMsrC6/5ApTmFgISg3 lazdTrnPmPdLzow7yla7Nzl2D4pVlMvE8cJJk= 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=+sjMIjM2/JFepdRAXpOHb7ghC5LhQeVZQ0Kayo5azeY=; b=qDfC3bqZIIUMua7sw4uQ4NjV+vObUkkYNdkyO8oNzXeUjSWMIBDesBzRkZ8HB7vA/n bWkBXVTMup0UE+hMa1kNds9FxZv7EVzNctwmQ4egf3vYRoukMsspcGiYZ4BkbrVsjurk AG+cZ7s9jtcJI6+0vgnXHQJ0tINRuKd6I5J4RqPNiyc49+gntqm85QRHZL5Rupv3Syyl 9nFq76aICTs4JDEcKf/Rcz44fqeDzG1gLL/aLoVS6bQaUpA35NY2uD6ILqrt5kekvebc aEnIy+aajyHT+3Y2B5NjEuzKnqni/9V+d1PtH6kVsyln3fIRFHCa/8NMFmS/Sl2Gw8QS YbUQ== X-Gm-Message-State: AOAM531XGqUflPComxXYwuB1LS/Z5zRXas+9EdrAOd6kJViifseZuHmj fe/6ntg/LRZ+2CxW7KZ0Uxz1NhR0KQsMGjUK6wYNZA== X-Google-Smtp-Source: ABdhPJx7T4CbUMQ5B2n8Maq8US8S/XJNlgydPVNLLLOLr6IH9mheDQ+RV1Tk59Uievz5SqNyI1kTrxdL9hey9Cb11rE= X-Received: by 2002:a05:6402:1d0b:: with SMTP id dg11mr3988736edb.212.1594727761659; Tue, 14 Jul 2020 04:56:01 -0700 (PDT) MIME-Version: 1.0 References: <20200705115021.GA1227929@kroah.com> <20200714065110.GA8047@amd> <4e92b851-ce9a-e2f6-3f9a-a4d47219d320@gmail.com> In-Reply-To: <4e92b851-ce9a-e2f6-3f9a-a4d47219d320@gmail.com> From: Miklos Szeredi Date: Tue, 14 Jul 2020 13:55:50 +0200 Message-ID: Subject: Re: [PATCH 0/3] readfile(2): a new syscall to make open/read/close faster To: Pavel Begunkov Cc: Pavel Machek , Greg KH , Jan Ziak <0xe2.0x9a.0x9b@gmail.com>, Linux API , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-man , Michael Kerrisk , shuah@kernel.org, Al Viro , io-uring@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Jul 14, 2020 at 1:36 PM Pavel Begunkov wrote: > > On 14/07/2020 11:07, Miklos Szeredi wrote: > > On Tue, Jul 14, 2020 at 8:51 AM Pavel Machek wrote: > >> > >> Hi! > >> > >>>> At first, I thought that the proposed system call is capable of > >>>> reading *multiple* small files using a single system call - which > >>>> would help increase HDD/SSD queue utilization and increase IOPS (I/O > >>>> operations per second) - but that isn't the case and the proposed > >>>> system call can read just a single file. > >>> > >>> If you want to do this for multple files, use io_ring, that's what it > >>> was designed for. I think Jens was going to be adding support for the > >>> open/read/close pattern to it as well, after some other more pressing > >>> features/fixes were finished. > >> > >> What about... just using io_uring for single file, too? I'm pretty > >> sure it can be wrapped in a library that is simple to use, avoiding > >> need for new syscall. > > > > Just wondering: is there a plan to add strace support to io_uring? > > And I don't just mean the syscalls associated with io_uring, but > > tracing the ring itself. > > What kind of support do you mean? io_uring is asynchronous in nature > with all intrinsic tracing/debugging/etc. problems of such APIs. > And there are a lot of handy trace points, are those not enough? > > Though, this can be an interesting project to rethink how async > APIs are worked with. Yeah, it's an interesting problem. The uring has the same events, as far as I understand, that are recorded in a multithreaded strace output (syscall entry, syscall exit); nothing more is needed. I do think this needs to be integrated into strace(1), otherwise the usefulness of that tool (which I think is *very* high) would go down drastically as io_uring usage goes up. Thanks, Miklos