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=unavailable 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 D4FF8C433E0 for ; Thu, 11 Mar 2021 05:31:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9800F64FD2 for ; Thu, 11 Mar 2021 05:31:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229524AbhCKFbQ (ORCPT ); Thu, 11 Mar 2021 00:31:16 -0500 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:56162 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229686AbhCKFbO (ORCPT ); Thu, 11 Mar 2021 00:31:14 -0500 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R481e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04423;MF=jefflexu@linux.alibaba.com;NM=1;PH=DS;RN=8;SR=0;TI=SMTPD_---0URNSjFi_1615440670; Received: from admindeMacBook-Pro-2.local(mailfrom:jefflexu@linux.alibaba.com fp:SMTPD_---0URNSjFi_1615440670) by smtp.aliyun-inc.com(127.0.0.1); Thu, 11 Mar 2021 13:31:10 +0800 Subject: Re: [dm-devel] [PATCH v5 03/12] block: add poll method to support bio-based IO polling To: Mike Snitzer Cc: axboe@kernel.dk, caspar@linux.alibaba.com, linux-block@vger.kernel.org, joseph.qi@linux.alibaba.com, dm-devel@redhat.com, mpatocka@redhat.com, io-uring@vger.kernel.org References: <20210303115740.127001-1-jefflexu@linux.alibaba.com> <20210303115740.127001-4-jefflexu@linux.alibaba.com> <20210310220122.GB23410@redhat.com> From: JeffleXu Message-ID: <7a934ba0-40b1-8611-4ed4-58a85923d6d9@linux.alibaba.com> Date: Thu, 11 Mar 2021 13:31:10 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210310220122.GB23410@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 3/11/21 6:01 AM, Mike Snitzer wrote: > On Wed, Mar 03 2021 at 6:57am -0500, > Jeffle Xu wrote: > >> ->poll_fn was introduced in commit ea435e1b9392 ("block: add a poll_fn >> callback to struct request_queue") to support bio-based queues such as >> nvme multipath, but was later removed in commit 529262d56dbe ("block: >> remove ->poll_fn"). >> >> Given commit c62b37d96b6e ("block: move ->make_request_fn to struct >> block_device_operations") restore the possibility of bio-based IO >> polling support by adding an ->poll method to gendisk->fops. >> >> Make blk_mq_poll() specific to blk-mq, while blk_bio_poll() is >> originally a copy from blk_mq_poll(), and is specific to bio-based >> polling. Currently hybrid polling is not supported by bio-based polling. >> >> Signed-off-by: Jeffle Xu >> --- >> block/blk-core.c | 58 ++++++++++++++++++++++++++++++++++++++++++ >> block/blk-mq.c | 22 +--------------- >> include/linux/blk-mq.h | 1 + >> include/linux/blkdev.h | 1 + >> 4 files changed, 61 insertions(+), 21 deletions(-) >> >> diff --git a/block/blk-core.c b/block/blk-core.c >> index fc60ff208497..6d7d53030d7c 100644 >> --- a/block/blk-core.c >> +++ b/block/blk-core.c >> @@ -1119,6 +1119,64 @@ blk_qc_t submit_bio(struct bio *bio) >> } >> EXPORT_SYMBOL(submit_bio); >> >> + > > Minor nit: Extra empty new line here? ^ Regards. Thanks. > > Otherwise, looks good (I like the end result of blk-mq and bio-based > polling being decoupled like hch suggested). > > Reviewed-by: Mike Snitzer > >> +static int blk_bio_poll(struct request_queue *q, blk_qc_t cookie, bool spin) >> +{ >> + long state; >> + struct gendisk *disk = queue_to_disk(q); >> + >> + state = current->state; >> + do { >> + int ret; >> + >> + ret = disk->fops->poll(q, cookie); >> + if (ret > 0) { >> + __set_current_state(TASK_RUNNING); >> + return ret; >> + } >> + >> + if (signal_pending_state(state, current)) >> + __set_current_state(TASK_RUNNING); >> + >> + if (current->state == TASK_RUNNING) >> + return 1; >> + if (ret < 0 || !spin) >> + break; >> + cpu_relax(); >> + } while (!need_resched()); >> + >> + __set_current_state(TASK_RUNNING); >> + return 0; >> +} >> + >> +/** >> + * blk_poll - poll for IO completions >> + * @q: the queue >> + * @cookie: cookie passed back at IO submission time >> + * @spin: whether to spin for completions >> + * >> + * Description: >> + * Poll for completions on the passed in queue. Returns number of >> + * completed entries found. If @spin is true, then blk_poll will continue >> + * looping until at least one completion is found, unless the task is >> + * otherwise marked running (or we need to reschedule). >> + */ >> +int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) >> +{ >> + if (!blk_qc_t_valid(cookie) || >> + !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) >> + return 0; >> + >> + if (current->plug) >> + blk_flush_plug_list(current->plug, false); >> + >> + if (queue_is_mq(q)) >> + return blk_mq_poll(q, cookie, spin); >> + else >> + return blk_bio_poll(q, cookie, spin); >> +} >> +EXPORT_SYMBOL_GPL(blk_poll); >> + >> /** >> * blk_cloned_rq_check_limits - Helper function to check a cloned request >> * for the new queue limits >> diff --git a/block/blk-mq.c b/block/blk-mq.c >> index d4d7c1caa439..214fa30b460a 100644 >> --- a/block/blk-mq.c >> +++ b/block/blk-mq.c >> @@ -3852,30 +3852,11 @@ static bool blk_mq_poll_hybrid(struct request_queue *q, >> return blk_mq_poll_hybrid_sleep(q, rq); >> } >> >> -/** >> - * blk_poll - poll for IO completions >> - * @q: the queue >> - * @cookie: cookie passed back at IO submission time >> - * @spin: whether to spin for completions >> - * >> - * Description: >> - * Poll for completions on the passed in queue. Returns number of >> - * completed entries found. If @spin is true, then blk_poll will continue >> - * looping until at least one completion is found, unless the task is >> - * otherwise marked running (or we need to reschedule). >> - */ >> -int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) >> +int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin) >> { >> struct blk_mq_hw_ctx *hctx; >> long state; >> >> - if (!blk_qc_t_valid(cookie) || >> - !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) >> - return 0; >> - >> - if (current->plug) >> - blk_flush_plug_list(current->plug, false); >> - >> hctx = q->queue_hw_ctx[blk_qc_t_to_queue_num(cookie)]; >> >> /* >> @@ -3917,7 +3898,6 @@ int blk_poll(struct request_queue *q, blk_qc_t cookie, bool spin) >> __set_current_state(TASK_RUNNING); >> return 0; >> } >> -EXPORT_SYMBOL_GPL(blk_poll); >> >> unsigned int blk_mq_rq_cpu(struct request *rq) >> { >> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h >> index 2c473c9b8990..6a7b693b9917 100644 >> --- a/include/linux/blk-mq.h >> +++ b/include/linux/blk-mq.h >> @@ -615,6 +615,7 @@ static inline void blk_rq_bio_prep(struct request *rq, struct bio *bio, >> } >> >> blk_qc_t blk_mq_submit_bio(struct bio *bio); >> +int blk_mq_poll(struct request_queue *q, blk_qc_t cookie, bool spin); >> void blk_mq_hctx_set_fq_lock_class(struct blk_mq_hw_ctx *hctx, >> struct lock_class_key *key); >> >> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h >> index b81a9fe015ab..9dc83c30e7bc 100644 >> --- a/include/linux/blkdev.h >> +++ b/include/linux/blkdev.h >> @@ -1866,6 +1866,7 @@ static inline void blk_ksm_unregister(struct request_queue *q) { } >> >> struct block_device_operations { >> blk_qc_t (*submit_bio) (struct bio *bio); >> + int (*poll)(struct request_queue *q, blk_qc_t cookie); >> int (*open) (struct block_device *, fmode_t); >> void (*release) (struct gendisk *, fmode_t); >> int (*rw_page)(struct block_device *, sector_t, struct page *, unsigned int); >> -- >> 2.27.0 >> > > -- > dm-devel mailing list > dm-devel@redhat.com > https://listman.redhat.com/mailman/listinfo/dm-devel > -- Thanks, Jeffle