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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A49ECC4332F for ; Mon, 17 Oct 2022 13:39:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=tGH+dvwO+cBr6xGBDZTVcarqRBH0PDZ8fa2KKBVr48c=; b=gPAfaLt8AvTM7o5qW/KeJW75fc 3JdPY2t0p/InVo3sNJUmGSAUPB7cCXn271qnIpDYK6L4w17bAdDYiaBZ2Z3YDdhvPQgA4ZEl/e7uI +vU9DU72RbxhlBCsSvZ6eHmQCY63+U4R7JmwTv05flfPz0JGWz/LjtymEL4QsfsVUkzOVP5HcCr9k g4/Bz0GoijGUVWaaQVMCM7ixV+nGLXq3pg/p4McfSvXBBNmaK3LOCjH5428/WbJRB5h7TZNtzZo1U hnlI6QhjVAnsjF6bUUoKnYXnmIyop/+50L0d4tEH11Gn3P0DOLeRSnFTO3pj/u26IA+lqpGO8uhuh OQAewtfw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1okQKn-00C9LU-Qk; Mon, 17 Oct 2022 13:39:13 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1okQKk-00C9HB-Ti for linux-nvme@lists.infradead.org; Mon, 17 Oct 2022 13:39:12 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id EE9FF68BFE; Mon, 17 Oct 2022 15:39:06 +0200 (CEST) Date: Mon, 17 Oct 2022 15:39:06 +0200 From: Christoph Hellwig To: Chao Leng Cc: linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, hch@lst.de, sagi@grimberg.me, kbusch@kernel.org, ming.lei@redhat.com, axboe@kernel.dk, "Paul E. McKenney" Subject: Re: [PATCH v2 1/2] blk-mq: add tagset quiesce interface Message-ID: <20221017133906.GA24492@lst.de> References: <20221013094450.5947-1-lengchao@huawei.com> <20221013094450.5947-2-lengchao@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221013094450.5947-2-lengchao@huawei.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221017_063911_124095_67F29486 X-CRM114-Status: GOOD ( 14.56 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, Oct 13, 2022 at 05:44:49PM +0800, Chao Leng wrote: > + rcu = kvmalloc(count * sizeof(*rcu), GFP_KERNEL); > + if (rcu) { > + list_for_each_entry(q, &set->tag_list, tag_set_list) { > + if (blk_queue_noquiesced(q)) > + continue; > + > + init_rcu_head(&rcu[i].head); > + init_completion(&rcu[i].completion); > + call_srcu(q->srcu, &rcu[i].head, wakeme_after_rcu); > + i++; > + } > + > + for (i = 0; i < count; i++) { > + wait_for_completion(&rcu[i].completion); > + destroy_rcu_head(&rcu[i].head); > + } > + kvfree(rcu); > + } else { > + list_for_each_entry(q, &set->tag_list, tag_set_list) > + synchronize_srcu(q->srcu); > + } Having to allocate a struct rcu_synchronize for each of the potentially many queues here is a bit sad. Pull just explained the start_poll_synchronize_rcu interfaces at ALPSS last week, so I wonder if something like that would also be feasible for SRCU, as that would come in really handy here.