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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 5C428C4360C for ; Tue, 8 Oct 2019 17:04:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B017217D7 for ; Tue, 8 Oct 2019 17:04:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726138AbfJHREG (ORCPT ); Tue, 8 Oct 2019 13:04:06 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:57232 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725900AbfJHREG (ORCPT ); Tue, 8 Oct 2019 13:04:06 -0400 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 0162E18FE7BAAD3BCC13; Wed, 9 Oct 2019 01:04:00 +0800 (CST) Received: from [127.0.0.1] (10.202.227.179) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.439.0; Wed, 9 Oct 2019 01:03:59 +0800 From: John Garry Subject: Re: [PATCH V3 3/5] blk-mq: stop to handle IO and drain IO before hctx becomes dead To: Ming Lei , Jens Axboe References: <20191008041821.2782-1-ming.lei@redhat.com> <20191008041821.2782-4-ming.lei@redhat.com> CC: , Bart Van Assche , Hannes Reinecke , Christoph Hellwig , "Thomas Gleixner" , Keith Busch Message-ID: <6fb931a8-48c6-0805-dc52-31f965e98803@huawei.com> Date: Tue, 8 Oct 2019 18:03:54 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 MIME-Version: 1.0 In-Reply-To: <20191008041821.2782-4-ming.lei@redhat.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.179] X-CFilter-Loop: Reflected Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 08/10/2019 05:18, Ming Lei wrote: > Before one CPU becomes offline, check if it is the last online CPU > of hctx. If yes, mark this hctx as BLK_MQ_S_INTERNAL_STOPPED, meantime > wait for completion of all in-flight IOs originated from this hctx. > > This way guarantees that there isn't any inflight IO before shutdowning > the managed IRQ line. > > Cc: John Garry > Cc: Bart Van Assche > Cc: Hannes Reinecke > Cc: Christoph Hellwig > Cc: Thomas Gleixner > Cc: Keith Busch Apart from nits, below, FWIW: Reviewed-by: John Garry > Signed-off-by: Ming Lei > --- > block/blk-mq-tag.c | 2 +- > block/blk-mq-tag.h | 2 ++ > block/blk-mq.c | 40 ++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 43 insertions(+), 1 deletion(-) > > diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c > index 008388e82b5c..31828b82552b 100644 > --- a/block/blk-mq-tag.c > +++ b/block/blk-mq-tag.c > @@ -325,7 +325,7 @@ static void bt_tags_for_each(struct blk_mq_tags *tags, struct sbitmap_queue *bt, > * true to continue iterating tags, false to stop. > * @priv: Will be passed as second argument to @fn. > */ > -static void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, > +void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, > busy_tag_iter_fn *fn, void *priv) > { > if (tags->nr_reserved_tags) > diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h > index 61deab0b5a5a..321fd6f440e6 100644 > --- a/block/blk-mq-tag.h > +++ b/block/blk-mq-tag.h > @@ -35,6 +35,8 @@ extern int blk_mq_tag_update_depth(struct blk_mq_hw_ctx *hctx, > extern void blk_mq_tag_wakeup_all(struct blk_mq_tags *tags, bool); > void blk_mq_queue_tag_busy_iter(struct request_queue *q, busy_iter_fn *fn, > void *priv); > +void blk_mq_all_tag_busy_iter(struct blk_mq_tags *tags, > + busy_tag_iter_fn *fn, void *priv); > > static inline struct sbq_wait_state *bt_wait_ptr(struct sbitmap_queue *bt, > struct blk_mq_hw_ctx *hctx) > diff --git a/block/blk-mq.c b/block/blk-mq.c > index a664f196782a..3384242202eb 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2225,8 +2225,46 @@ int blk_mq_alloc_rqs(struct blk_mq_tag_set *set, struct blk_mq_tags *tags, > return -ENOMEM; > } > > +static bool blk_mq_count_inflight_rq(struct request *rq, void *data, > + bool reserved) > +{ > + unsigned *count = data; > + > + if ((blk_mq_rq_state(rq) == MQ_RQ_IN_FLIGHT)) nit: extra parentheses > + (*count)++; > + > + return true; > +} > + > +static unsigned blk_mq_tags_inflight_rqs(struct blk_mq_tags *tags) > +{ > + unsigned count = 0; > + > + blk_mq_all_tag_busy_iter(tags, blk_mq_count_inflight_rq, &count); > + > + return count; > +} > + > +static void blk_mq_hctx_drain_inflight_rqs(struct blk_mq_hw_ctx *hctx) > +{ > + while (1) { > + if (!blk_mq_tags_inflight_rqs(hctx->tags)) > + break; > + msleep(5); > + } > +} > + > static int blk_mq_hctx_notify_online(unsigned int cpu, struct hlist_node *node) > { > + struct blk_mq_hw_ctx *hctx = hlist_entry_safe(node, > + struct blk_mq_hw_ctx, cpuhp_online); > + nit: we could make this a little neater by using an intermediate variable for hctx->cpumask: struct cpumask *cpumask = hctx->cpumask; if ((cpumask_next_and(-1, cpumask, cpu_online_mask) == cpu) && ... > + if ((cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) == cpu) && > + (cpumask_next_and(cpu, hctx->cpumask, cpu_online_mask) >= > + nr_cpu_ids)) { > + set_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state); > + blk_mq_hctx_drain_inflight_rqs(hctx); > + } > return 0; > } > > @@ -2246,6 +2284,8 @@ static int blk_mq_hctx_notify_dead(unsigned int cpu, struct hlist_node *node) > ctx = __blk_mq_get_ctx(hctx->queue, cpu); > type = hctx->type; > > + clear_bit(BLK_MQ_S_INTERNAL_STOPPED, &hctx->state); > + > spin_lock(&ctx->lock); > if (!list_empty(&ctx->rq_lists[type])) { > list_splice_init(&ctx->rq_lists[type], &tmp); >