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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, 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 23D03C433DB for ; Tue, 16 Mar 2021 02:42:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D35C365057 for ; Tue, 16 Mar 2021 02:42:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230227AbhCPCla (ORCPT ); Mon, 15 Mar 2021 22:41:30 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:56187 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231214AbhCPClM (ORCPT ); Mon, 15 Mar 2021 22:41:12 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R101e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0US4Vh1x_1615862469; Received: from B-25KNML85-0107.local(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0US4Vh1x_1615862469) by smtp.aliyun-inc.com(127.0.0.1); Tue, 16 Mar 2021 10:41:10 +0800 Subject: Re: [PATCH] io_uring: don't iterate ctx list to update sq_thread_idle To: Pavel Begunkov , Jens Axboe Cc: io-uring@vger.kernel.org, Joseph Qi References: <1615798614-1044-1-git-send-email-haoxu@linux.alibaba.com> <4caf1b47-56fd-85d8-87d0-ab7d43ac2914@gmail.com> From: Hao Xu Message-ID: Date: Tue, 16 Mar 2021 10:41:09 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <4caf1b47-56fd-85d8-87d0-ab7d43ac2914@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 2021/3/15 下午6:49, Pavel Begunkov 写道: > On 15/03/2021 08:56, Hao Xu wrote: >> sqd->sq_thread_idle can be updated by a simple max(), rather than >> iterating the whole ctx list to get the max one. > > I left it as a more fool proof option. Do you have a performance issue > with it? E.g. dozens rings sharing a single SQPOLL and constantly adding > new ones. Currently no performance cases, just happen to see this and make the code change. > >> >> Signed-off-by: Hao Xu >> --- >> fs/io_uring.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index a4bce17af506..17697b9890e3 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -7871,7 +7871,7 @@ static int io_sq_offload_create(struct io_ring_ctx *ctx, >> ret = -ENXIO; >> } else { >> list_add(&ctx->sqd_list, &sqd->ctx_list); >> - io_sqd_update_thread_idle(sqd); >> + sqd->sq_thread_idle = max(sqd->sq_thread_idle, ctx->sq_thread_idle); >> } >> io_sq_thread_unpark(sqd); >> >> >