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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,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 D28F0C433E2 for ; Sat, 16 May 2020 09:20:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B30192076A for ; Sat, 16 May 2020 09:20:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726202AbgEPJUw (ORCPT ); Sat, 16 May 2020 05:20:52 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:58144 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726271AbgEPJUw (ORCPT ); Sat, 16 May 2020 05:20:52 -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=e01e04394;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0Tyh2mEi_1589620846; Received: from 30.39.188.132(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0Tyh2mEi_1589620846) by smtp.aliyun-inc.com(127.0.0.1); Sat, 16 May 2020 17:20:46 +0800 Subject: Re: [PATCH RFC} io_uring: io_kiocb alloc cache To: Jens Axboe , io-uring Cc: joseph qi , Jiufei Xue , Pavel Begunkov References: <492bb956-a670-8730-a35f-1d878c27175f@kernel.dk> <70602a13-f6c9-e8a8-1035-6f148ba2d6d7@kernel.dk> From: Xiaoguang Wang Message-ID: Date: Sat, 16 May 2020 17:20:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org hi, >> For the latter, it's totally feasible to just have the io_kiocb on >> stack. The downside is if we need to go the slower path, then we need to >> alloc an io_kiocb then and copy it. But maybe that's OK... I'll play >> with it. > > Can you try this with your microbenchmark? Just curious what it looks > like for that test case if we completely take slab alloc+free out of it. I run two rounds, every runs 300 seconds: 1st IOPS: 6231528, about 15% improvement 2nd IOPS: 6173959 about 14% improvement. Looks better for nop tests :) Regards, Xiaoguang Wang > > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index d2e37215d05a..4ecd6bd38f02 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -525,6 +525,7 @@ enum { > REQ_F_POLLED_BIT, > REQ_F_BUFFER_SELECTED_BIT, > REQ_F_NO_FILE_TABLE_BIT, > + REQ_F_STACK_REQ_BIT, > > /* not a real bit, just to check we're not overflowing the space */ > __REQ_F_LAST_BIT, > @@ -580,6 +581,8 @@ enum { > REQ_F_BUFFER_SELECTED = BIT(REQ_F_BUFFER_SELECTED_BIT), > /* doesn't need file table for this request */ > REQ_F_NO_FILE_TABLE = BIT(REQ_F_NO_FILE_TABLE_BIT), > + /* on-stack req */ > + REQ_F_STACK_REQ = BIT(REQ_F_STACK_REQ_BIT), > }; > > struct async_poll { > @@ -695,10 +698,14 @@ struct io_op_def { > unsigned pollout : 1; > /* op supports buffer selection */ > unsigned buffer_select : 1; > + /* op can use stack req */ > + unsigned stack_req : 1; > }; > > static const struct io_op_def io_op_defs[] = { > - [IORING_OP_NOP] = {}, > + [IORING_OP_NOP] = { > + .stack_req = 1, > + }, > [IORING_OP_READV] = { > .async_ctx = 1, > .needs_mm = 1, > @@ -1345,7 +1352,8 @@ static void __io_req_aux_free(struct io_kiocb *req) > if (req->flags & REQ_F_NEED_CLEANUP) > io_cleanup_req(req); > > - kfree(req->io); > + if (req->io) > + kfree(req->io); > if (req->file) > io_put_file(req, req->file, (req->flags & REQ_F_FIXED_FILE)); > if (req->task) > @@ -1370,6 +1378,8 @@ static void __io_free_req(struct io_kiocb *req) > } > > percpu_ref_put(&req->ctx->refs); > + if (req->flags & REQ_F_STACK_REQ) > + return; > if (likely(!io_is_fallback_req(req))) > kmem_cache_free(req_cachep, req); > else > @@ -5784,12 +5794,10 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req, > * link list. > */ > req->sequence = ctx->cached_sq_head - ctx->cached_sq_dropped; > - req->opcode = READ_ONCE(sqe->opcode); > req->user_data = READ_ONCE(sqe->user_data); > req->io = NULL; > req->file = NULL; > req->ctx = ctx; > - req->flags = 0; > /* one is dropped after submission, the other at completion */ > refcount_set(&req->refs, 2); > req->task = NULL; > @@ -5839,6 +5847,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, > { > struct io_submit_state state, *statep = NULL; > struct io_kiocb *link = NULL; > + struct io_kiocb stack_req; > int i, submitted = 0; > > /* if we have a backlog and couldn't flush it all, return BUSY */ > @@ -5865,20 +5874,31 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, > for (i = 0; i < nr; i++) { > const struct io_uring_sqe *sqe; > struct io_kiocb *req; > - int err; > + int err, op; > > sqe = io_get_sqe(ctx); > if (unlikely(!sqe)) { > io_consume_sqe(ctx); > break; > } > - req = io_alloc_req(ctx, statep); > - if (unlikely(!req)) { > - if (!submitted) > - submitted = -EAGAIN; > - break; > + > + op = READ_ONCE(sqe->opcode); > + > + if (io_op_defs[op].stack_req) { > + req = &stack_req; > + req->flags = REQ_F_STACK_REQ; > + } else { > + req = io_alloc_req(ctx, statep); > + if (unlikely(!req)) { > + if (!submitted) > + submitted = -EAGAIN; > + break; > + } > + req->flags = 0; > } > > + req->opcode = op; > + > err = io_init_req(ctx, req, sqe, statep, async); > io_consume_sqe(ctx); > /* will complete beyond this point, count as submitted */ >