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=-5.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 7FA23C433FB for ; Tue, 28 Jul 2020 07:19:08 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 50B99207E8 for ; Tue, 28 Jul 2020 07:19:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="AO3rkMAY" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50B99207E8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=+Okge/ofSG99QMvug5xV4cFjxmLf3UkkMaaDC6rE40Y=; b=AO3rkMAYCdRf/0BP1rS1t59CY DRSovhMwBMOW0ehtkHCeCYnSlhl6fYemGbVL0L7JjxUJAbyX0yeHAIw1SSdBt3PLuqmA6LAQ0HJXU 8h4OyZGLZSk3Qt8wBGHf0oLIT1NfefVgci5QjlXYzg5k5EectnhORkL1yrZgbqDvDqLUEQ8kyRX22 ZZ7nQFSuXcg7JcSwU8Sf1wRZA5a0LDAZp5pq+FWBEQ3ITgHFWJS/5X3LGXAnxDaCE0HFYCeRUhCxd AU0lYwCFxn3znIWxjJ/qLnB09iL4GVJt5/oaHSuhurEOxapIiZxdOXf6Dt/Op+2dgvf/Imiqmd9KQ l7INrB2uQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0JtB-0007v1-SC; Tue, 28 Jul 2020 07:19:05 +0000 Received: from verein.lst.de ([213.95.11.211]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0Jt9-0007uN-0U for linux-nvme@lists.infradead.org; Tue, 28 Jul 2020 07:19:03 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 32BD868B05; Tue, 28 Jul 2020 09:19:00 +0200 (CEST) Date: Tue, 28 Jul 2020 09:18:59 +0200 From: Christoph Hellwig To: Sagi Grimberg Subject: Re: [PATCH v5 1/2] blk-mq: add tagset quiesce interface Message-ID: <20200728071859.GA21629@lst.de> 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> 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-20200728_031903_222703_4F4B52EE X-CRM114-Status: GOOD ( 12.65 ) 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 , "Paul E. McKenney" , 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 I like the tagset based interface. But the idea of doing a per-hctx allocation and wait doesn't seem very scalable. Paul, do you have any good idea for an interface that waits on multiple srcu heads? As far as I can tell we could just have a single global completion and counter, and each call_srcu would just just decrement it and then the final one would do the wakeup. It would just be great to figure out a way to keep the struct rcu_synchronize and counter on stack to avoid an allocation. But if we can't do with an on-stack object I'd much rather just embedd the rcu_head in the hw_ctx. _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme