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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C928C433F5 for ; Fri, 26 Nov 2021 08:52:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345536AbhKZIzs (ORCPT ); Fri, 26 Nov 2021 03:55:48 -0500 Received: from out4436.biz.mail.alibaba.com ([47.88.44.36]:55700 "EHLO out4436.biz.mail.alibaba.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353511AbhKZIxr (ORCPT ); Fri, 26 Nov 2021 03:53:47 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R211e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0UyLw5Vf_1637916631; Received: from B-25KNML85-0107.local(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0UyLw5Vf_1637916631) by smtp.aliyun-inc.com(127.0.0.1); Fri, 26 Nov 2021 16:50:32 +0800 Subject: Re: Question about sendfile To: Pavel Begunkov Cc: Jens Axboe , io-uring , Joseph Qi References: <6a7ceb04-3503-7300-8089-86c106a95e96@linux.alibaba.com> <4831bcfd-ce4a-c386-c5b2-a1417a23c500@gmail.com> From: Hao Xu Message-ID: <1414c8f9-e454-fb5a-7e44-cead5bbd61ea@linux.alibaba.com> Date: Fri, 26 Nov 2021 16:50:31 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <4831bcfd-ce4a-c386-c5b2-a1417a23c500@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org 在 2021/7/7 下午10:16, Pavel Begunkov 写道: > On 7/3/21 11:47 AM, Hao Xu wrote: >> Hi Pavel, >> I found this mail about sendfile in the maillist, may I ask why it's not >> good to have one pipe each for a io-wq thread. >> https://lore.kernel.org/io-uring/94dbbb15-4751-d03c-01fd-d25a0fe98e25@gmail.com/ > > IIRC, it's one page allocated for each such task, which is bearable but > don't like yet another chunk of uncontrollable implicit state. If there > not a bunch of active workers, IFAIK there is no way to force them to > drop their pipes. > > I also don't remember the restrictions on the sendfile and what's with > the eternal question of "what to do if the write part of sendfile has > failed". Hi Pavel, Could you explain this question a little bit.., is there any special concern? What I thought is sendfile does what it does,when it fails, it will return -1 and errno is set appropriately. > > Though, workers are now much more alike to user threads, so there > should be less of concern. And even though my gut feeling don't like > them, it may actually be useful. Do you have a good use case where > explicit pipes don't work well? >