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 7305FC433E3 for ; Wed, 15 Jul 2020 08:41:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5270720663 for ; Wed, 15 Jul 2020 08:41:36 +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="joTTxszS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730327AbgGOIlg (ORCPT ); Wed, 15 Jul 2020 04:41:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729373AbgGOIlf (ORCPT ); Wed, 15 Jul 2020 04:41:35 -0400 Received: from mail-ed1-x543.google.com (mail-ed1-x543.google.com [IPv6:2a00:1450:4864:20::543]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A6434C08C5C1 for ; Wed, 15 Jul 2020 01:41:34 -0700 (PDT) Received: by mail-ed1-x543.google.com with SMTP id d16so973471edz.12 for ; Wed, 15 Jul 2020 01:41:34 -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=J4RPEf69RMf6fMrFPs7gvn650I5l4fPXkmLiZzrYicg=; b=joTTxszSLFMvayIfPbb55BXWK7XCzUWZDla2m5tAeog6qXLfmJE5dj+uRo2NBF9wZ/ F7i8zd8hr0+Qxym6zB6l97h72NSaZ/5NKdHBEnj5J1feDVUpr1YfOMLXfk4KLNiTdWYK 3mrklvsXTJ1W+NqzIijFYhkfbdrl3pBNpY49Y= 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=J4RPEf69RMf6fMrFPs7gvn650I5l4fPXkmLiZzrYicg=; b=q7kCgRpONl0g5mgUFFzLqPuPHt8qtHFfmGj3IaUSQhmyzw38Tk/iHE9+vjN1vHzh7a 0xH87FC6rw4d6Koerj7D1oN3MUERpbWKCGuKc7iR7v7UNDmjTZX3WEn2hV3FVnJpOXs6 Qt/QtYrceknRxkNdjzlIn/hzLJ3Wu4GOCPs2Y/pv2YQRgGa9gyuxemRbYT7UV7/p4SwW GZIxqUso0bCN7pbbQo4jl18CEQT6rN25ZvNm14DFKNmPFQJ911R7tZUuPPHt39VLvCoC G+6NhOjfnfm2elgjQ+/2TnPw0XlWelj6OqA9+uKJQQI71bEvQP9b8IRbZIR6lSvxEK90 jqcg== X-Gm-Message-State: AOAM533JMFMxGMtLH78JJXbeWYS+HMOftL46u3Y8w8eZw4pKDKvXUvMO HALamlZH6SHYNAw66HWQuF4bfJ8BvZcwmNP5XSqjcA== X-Google-Smtp-Source: ABdhPJxiUoXSY8oQTuQyEBhp5lraS2n1iwGYDCrETHXVLFmYYXHH1CsTFd5Uc/EepPXHKcXFh5OP0Y7UW1nxbUoUAJg= X-Received: by 2002:a05:6402:1687:: with SMTP id a7mr8448226edv.358.1594802493290; Wed, 15 Jul 2020 01:41:33 -0700 (PDT) MIME-Version: 1.0 References: <20200705115021.GA1227929@kroah.com> <20200714065110.GA8047@amd> <4e92b851-ce9a-e2f6-3f9a-a4d47219d320@gmail.com> <7584d754-2044-a892-cf29-65259b9c4eb1@gmail.com> In-Reply-To: <7584d754-2044-a892-cf29-65259b9c4eb1@gmail.com> From: Miklos Szeredi Date: Wed, 15 Jul 2020 10:41:22 +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: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Wed, Jul 15, 2020 at 10:33 AM Pavel Begunkov wrote: > > On 14/07/2020 14:55, Miklos Szeredi wrote: > > 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. > > Not touching the topic of usefulness of strace + io_uring, but I'd rather > have a tool that solves a problem, than a problem that created and honed > for a tool. Sorry, I'm not getting the metaphor. Can you please elaborate? Thanks, Miklos