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=-6.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 184C5C433E3 for ; Wed, 29 Jul 2020 00:43:13 +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 DE0922076E for ; Wed, 29 Jul 2020 00:43:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="WGgu7ERg" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE0922076E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=grimberg.me 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-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=pBc/YM6eCFK+9LoRZI+T8SSNFt4Po0yGJDB53f3eiTQ=; b=WGgu7ERgtaUFAH4sAYlYfmqfo cpSouMrLgNIGkzVwXNZgHsyhEo6gnpReQtKxiWfWrGyINgElcdumkihriEjVAI3npkq4rDtx2dllf eqTS1yXfJPlwMN1LHv0m4HG8Fsw2FRdMQIQAjaMfo5pI4ML02wiWBIS8/N18ps1jupGy8XhdxeMs+ E3azG+GocSIX6vWbxZohwWWVT5Y1DsjRIuY3qCMwOJgMPgulkzAGgTDx73SXFe9+KJFV+OZpJYSeH U6cRHqdzbOJld+i0bndHlyyYoGF7QlehBpXS/lQ5WemMYdz4FK09a00Y/9kKmaIPfkE6Ez6pmcxOl 2El9o8qYA==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0aBY-0004i1-0y; Wed, 29 Jul 2020 00:43:08 +0000 Received: from mail-pg1-f193.google.com ([209.85.215.193]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1k0aBV-0004hZ-Sv for linux-nvme@lists.infradead.org; Wed, 29 Jul 2020 00:43:06 +0000 Received: by mail-pg1-f193.google.com with SMTP id l63so13294262pge.12 for ; Tue, 28 Jul 2020 17:43:05 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Q621nujP6PGe0N0JjbEojimC1WUZHW4/irnI2wZeTfk=; b=bAGnkUxVxS8eMc4USuD/BT4msggUfJEL0ID4YB6bs1IkI3sJdNAJw/2DFG+Z6hS9zr BDEINhyuzAH3eCdD4K1tsKRfYwpJXOl7z5Ytevlk+bJe+dkqgXQfigLh7X6uJXZMEpOC 9SCp7L13Rd/6csXOErfGMXX7dNtujife8lcsXAk3QX2ty9eeS7Rzab3MPqRhlwblijmd uNh9HVhTLUB4VLO+8RU7ayrtArxwcZinOFK9K7ZB8xLKqfeDP8+RJTUWhB1oacd73Wcn +UOhQDFFIE/2klsSc7Eofmg3iLsJfNl3/WIFciYdlNijDOJkylVBy0DYiVcyNgZ2oVNF GFAQ== X-Gm-Message-State: AOAM53179bXpZ+HWZRCrNq5ZzHSLIQbm6zllPE4FWC1goegvHQrasM2v p80YmXNMgn4J0LwjiB1mBCQ= X-Google-Smtp-Source: ABdhPJxQODq0xK6fvW2V3KNlqM/yc77wLReKq8n97sRZZjRInGdpD0ykPKVa1bZJXKGHsK7q7hfsmw== X-Received: by 2002:a62:77d2:: with SMTP id s201mr9201832pfc.213.1595983384823; Tue, 28 Jul 2020 17:43:04 -0700 (PDT) Received: from ?IPv6:2601:647:4802:9070:fcc5:69d8:6e20:4fd1? ([2601:647:4802:9070:fcc5:69d8:6e20:4fd1]) by smtp.gmail.com with ESMTPSA id a16sm229980pgj.27.2020.07.28.17.43.03 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Jul 2020 17:43:04 -0700 (PDT) Subject: Re: [PATCH v5 1/2] blk-mq: add tagset quiesce interface To: paulmck@kernel.org References: <20200727231022.307602-1-sagi@grimberg.me> <20200727231022.307602-2-sagi@grimberg.me> <20200728071859.GA21629@lst.de> <20200728091633.GB1326626@T590> <20200728135436.GP9247@paulmck-ThinkPad-P72> <20200729003124.GT9247@paulmck-ThinkPad-P72> From: Sagi Grimberg Message-ID: <07c90cf1-bb6f-a343-b0bf-4c91b9acb431@grimberg.me> Date: Tue, 28 Jul 2020 17:43:02 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200729003124.GT9247@paulmck-ThinkPad-P72> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200728_204305_964138_45822E51 X-CRM114-Status: GOOD ( 16.75 ) 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, Ming Lei , linux-block@vger.kernel.org, Chao Leng , Keith Busch , Ming Lin , Christoph Hellwig Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org >> Dynamically allocating each one is possible but not very scalable. >> >> The question is if there is some way, we can do this with on-stack >> or a single on-heap rcu_head or equivalent that can achieve the same >> effect. > > If the hctx structures are guaranteed to stay put, you could count > them and then do a single allocation of an array of rcu_head structures > (or some larger structure containing an rcu_head structure, if needed). > You could then sequence through this array, consuming one rcu_head per > hctx as you processed it. Once all the callbacks had been invoked, > it would be safe to free the array. > > Sounds too simple, though. So what am I missing? We don't want higher-order allocations... _______________________________________________ Linux-nvme mailing list Linux-nvme@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-nvme