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 3B23CC433F5 for ; Fri, 24 Sep 2021 04:28:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 195D261100 for ; Fri, 24 Sep 2021 04:28:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231256AbhIXE3m (ORCPT ); Fri, 24 Sep 2021 00:29:42 -0400 Received: from out30-130.freemail.mail.aliyun.com ([115.124.30.130]:43987 "EHLO out30-130.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229853AbhIXE3m (ORCPT ); Fri, 24 Sep 2021 00:29:42 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R491e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0UpOMucm_1632457688; Received: from legedeMacBook-Pro.local(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0UpOMucm_1632457688) by smtp.aliyun-inc.com(127.0.0.1); Fri, 24 Sep 2021 12:28:08 +0800 Subject: Re: [RFC 3/3] io_uring: try to batch poll request completion To: Pavel Begunkov , io-uring@vger.kernel.org Cc: axboe@kernel.dk References: <20210922123417.2844-1-xiaoguang.wang@linux.alibaba.com> <20210922123417.2844-4-xiaoguang.wang@linux.alibaba.com> From: Xiaoguang Wang Message-ID: <61f88377-9950-7b7f-c350-693c2305449e@linux.alibaba.com> Date: Fri, 24 Sep 2021 12:28:07 +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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org hi, > On 9/22/21 1:34 PM, Xiaoguang Wang wrote: >> For an echo-server based on io_uring's IORING_POLL_ADD_MULTI feature, >> only poll request are completed in task work, normal read/write >> requests are issued when user app sees cqes on corresponding poll >> requests, and they will mostly read/write data successfully, which >> don't need task work. So at least for echo-server model, batching >> poll request completion properly will give benefits. >> >> Currently don't find any appropriate place to store batched poll >> requests, put them in struct io_submit_state temporarily, which I >> think it'll need rework in future. >> >> Signed-off-by: Xiaoguang Wang >> --- >> fs/io_uring.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 63 insertions(+), 1 deletion(-) >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index 6fdfb688cf91..14118388bfc6 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -321,6 +321,11 @@ struct io_submit_state { >> */ >> struct io_kiocb *compl_reqs[IO_COMPL_BATCH]; >> unsigned int compl_nr; >> + >> + struct io_kiocb *poll_compl_reqs[IO_COMPL_BATCH]; >> + bool poll_req_status[IO_COMPL_BATCH]; >> + unsigned int poll_compl_nr; >> + >> /* inline/task_work completion list, under ->uring_lock */ >> struct list_head free_list; >> >> @@ -2093,6 +2098,8 @@ static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked) >> percpu_ref_put(&ctx->refs); >> } >> >> +static void io_poll_flush_completions(struct io_ring_ctx *ctx, bool *locked); >> + >> static void tctx_task_work(struct callback_head *cb) >> { >> bool locked = false; >> @@ -2103,8 +2110,11 @@ static void tctx_task_work(struct callback_head *cb) >> while (1) { >> struct io_wq_work_node *node; >> >> - if (!tctx->task_list.first && locked && ctx->submit_state.compl_nr) >> + if (!tctx->task_list.first && locked && (ctx->submit_state.compl_nr || >> + ctx->submit_state.poll_compl_nr)) { > io_submit_flush_completions() shouldn't be called if there are no requests... And the > check is already inside for-next, will be > > if (... && locked) { > io_submit_flush_completions(); > if (poll_compl_nr) > io_poll_flush_completions(); OK, thanks for pointing this, and I have dropped the poll request completion batching patch, since it shows performance fluctuations, hard to say whether it's useful. Regards, Xiaoguang Wang > } > >> io_submit_flush_completions(ctx); >> + io_poll_flush_completions(ctx, &locked); >> + } >> >> spin_lock_irq(&tctx->task_lock); >> node = tctx->task_list.first; >> @@ -5134,6 +5144,49 @@ static inline bool io_poll_complete(struct io_kiocb *req, __poll_t mask) >> static bool __io_poll_remove_one(struct io_kiocb *req, >> struct io_poll_iocb *poll, bool do_cancel); >> >> +static void io_poll_flush_completions(struct io_ring_ctx *ctx, bool *locked) >> + __must_hold(&ctx->uring_lock) >> +{ >> + struct io_submit_state *state = &ctx->submit_state; >> + struct io_kiocb *req, *nxt; >> + int i, nr = state->poll_compl_nr; >> + bool done, skip_done = true; >> + >> + spin_lock(&ctx->completion_lock); >> + for (i = 0; i < nr; i++) { >> + req = state->poll_compl_reqs[i]; >> + done = __io_poll_complete(req, req->result); > I believe we first need to fix all the poll problems and lay out something more intuitive > than the current implementation, or it'd be pure hell to do afterwards. > > Can be a nice addition, curious about numbers as well. > >