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Sun, 26 Jul 2020 05:31:45 -0400 X-MC-Unique: rj0vGx7EP4yvMW3S375rfg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id F04C01902EA2; Sun, 26 Jul 2020 09:31:43 +0000 (UTC) Received: from T590 (ovpn-12-72.pek2.redhat.com [10.72.12.72]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E47485DA30; Sun, 26 Jul 2020 09:31:36 +0000 (UTC) Date: Sun, 26 Jul 2020 17:31:32 +0800 From: Ming Lei To: Sagi Grimberg Subject: Re: [PATCH v3 1/2] blk-mq: add async quiesce interface Message-ID: <20200726093132.GD1110104@T590> References: <20200726002301.145627-1-sagi@grimberg.me> <20200726002301.145627-2-sagi@grimberg.me> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200726002301.145627-2-sagi@grimberg.me> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200726_053150_938217_3FA3F2F3 X-CRM114-Status: GOOD ( 20.03 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, Chao Leng , Keith Busch , Christoph Hellwig Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org Hi Sagi, On Sat, Jul 25, 2020 at 05:23:00PM -0700, Sagi Grimberg wrote: > Drivers that may have to quiesce a large amount of request queues at once > (e.g. controller or adapter reset). These drivers would benefit from an > async quiesce interface such that the can trigger quiesce asynchronously > and wait for all in parallel. > > This leaves the synchronization responsibility to the driver, but adds > a convenient interface to quiesce async and wait in a single pass. > > Signed-off-by: Sagi Grimberg > --- > block/blk-mq.c | 32 ++++++++++++++++++++++++++++++++ > include/linux/blk-mq.h | 4 ++++ > 2 files changed, 36 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index abcf590f6238..60d137265bd9 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -209,6 +209,38 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) > } > EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); > > +void blk_mq_quiesce_queue_async(struct request_queue *q) > +{ > + struct blk_mq_hw_ctx *hctx; > + unsigned int i; > + > + blk_mq_quiesce_queue_nowait(q); > + > + queue_for_each_hw_ctx(q, hctx, i) { > + init_completion(&hctx->rcu_sync.completion); > + init_rcu_head(&hctx->rcu_sync.head); > + if (hctx->flags & BLK_MQ_F_BLOCKING) > + call_srcu(hctx->srcu, &hctx->rcu_sync.head, > + wakeme_after_rcu); > + else > + call_rcu(&hctx->rcu_sync.head, > + wakeme_after_rcu); > + } Looks not necessary to do anything in case of !BLK_MQ_F_BLOCKING, and single synchronize_rcu() is OK for all hctx during waiting. > +} > +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_async); > + > +void blk_mq_quiesce_queue_async_wait(struct request_queue *q) > +{ > + struct blk_mq_hw_ctx *hctx; > + unsigned int i; > + > + queue_for_each_hw_ctx(q, hctx, i) { > + wait_for_completion(&hctx->rcu_sync.completion); > + destroy_rcu_head(&hctx->rcu_sync.head); > + } > +} > +EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_async_wait); > + > /** > * blk_mq_quiesce_queue() - wait until all ongoing dispatches have finished > * @q: request queue. > diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h > index 23230c1d031e..5536e434311a 100644 > --- a/include/linux/blk-mq.h > +++ b/include/linux/blk-mq.h > @@ -5,6 +5,7 @@ > #include > #include > #include > +#include > > struct blk_mq_tags; > struct blk_flush_queue; > @@ -170,6 +171,7 @@ struct blk_mq_hw_ctx { > */ > struct list_head hctx_list; > > + struct rcu_synchronize rcu_sync; The above struct takes at least 5 words, and I'd suggest to avoid it, and the hctx->srcu should be re-used for waiting BLK_MQ_F_BLOCKING. Meantime !BLK_MQ_F_BLOCKING doesn't need it. Thanks, Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme