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=-5.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 C104BC07E9A for ; Wed, 14 Jul 2021 03:50:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9192761370 for ; Wed, 14 Jul 2021 03:50:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237725AbhGNDxJ (ORCPT ); Tue, 13 Jul 2021 23:53:09 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:37557 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237655AbhGNDxJ (ORCPT ); Tue, 13 Jul 2021 23:53:09 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R201e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Ufk6rVH_1626234615; Received: from B-25KNML85-0107.local(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0Ufk6rVH_1626234615) by smtp.aliyun-inc.com(127.0.0.1); Wed, 14 Jul 2021 11:50:16 +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: Date: Wed, 14 Jul 2021 11:50:15 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 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". I haven't dig into it deeply, will do some investigation. > > 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? The thing is two linked splice sqes may be cut off in shared sqthread case. >