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Mon, 27 Jul 2020 21:40:51 -0400 X-MC-Unique: IQ4Zp378Nv6c-sGQCI9_0w-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 311DC80183C; Tue, 28 Jul 2020 01:40:50 +0000 (UTC) Received: from T590 (ovpn-12-109.pek2.redhat.com [10.72.12.109]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9D1CF69323; Tue, 28 Jul 2020 01:40:42 +0000 (UTC) Date: Tue, 28 Jul 2020 09:40:38 +0800 From: Ming Lei To: Sagi Grimberg Subject: Re: [PATCH v5 1/2] blk-mq: add tagset quiesce interface Message-ID: <20200728014038.GA1305646@T590> References: <20200727231022.307602-1-sagi@grimberg.me> <20200727231022.307602-2-sagi@grimberg.me> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200727231022.307602-2-sagi@grimberg.me> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200727_214056_830214_EC25913A X-CRM114-Status: GOOD ( 24.64 ) 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 , Ming Lin , 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 On Mon, Jul 27, 2020 at 04:10:21PM -0700, Sagi Grimberg wrote: > drivers that have shared tagsets may need to quiesce potentially a lot > of request queues that all share a single tagset (e.g. nvme). Add an interface > to quiesce all the queues on a given tagset. This interface is useful because > it can speedup the quiesce by doing it in parallel. > > For tagsets that have BLK_MQ_F_BLOCKING set, we use call_srcu to all hctxs > in parallel such that all of them wait for the same rcu elapsed period with > a per-hctx heap allocated rcu_synchronize. for tagsets that don't have > BLK_MQ_F_BLOCKING set, we simply call a single synchronize_rcu as this is > sufficient. > > Signed-off-by: Sagi Grimberg > --- > block/blk-mq.c | 66 ++++++++++++++++++++++++++++++++++++++++++ > include/linux/blk-mq.h | 4 +++ > 2 files changed, 70 insertions(+) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index abcf590f6238..c37e37354330 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -209,6 +209,42 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) > } > EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); > > +static void blk_mq_quiesce_blocking_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) { > + WARN_ON_ONCE(!(hctx->flags & BLK_MQ_F_BLOCKING)); > + hctx->rcu_sync = kmalloc(sizeof(*hctx->rcu_sync), GFP_KERNEL); > + if (!hctx->rcu_sync) > + continue; This approach of quiesce/unquiesce tagset is good abstraction. Just one more thing, please allocate a rcu_sync array because hctx is supposed to not store scratch stuff. thanks, Ming _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme