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 7DE88D2E014 for ; Wed, 23 Oct 2024 05:20:20 +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=0o14UPFmhT8+3zIRNxd5qxLHsoDDbIO5RH45r+WkLpw=; b=mzUK5tSKTXROLtEJ0knBz8VVGC SC27phYLJa/pfNpRqGSY6z8w6/kcCFYekKY3bHjrFvR1TnK7BLpt7oQ+j2vRHMc3dKF4SKLFCi+Vi SSS49AsYHvTVDuUBZieuJYdT26TPlGIBbA27Ujx5wnfNfTYBizQu8c5KQFPfBBYzJP9U+9aO7cxbK pDkmU0idhd8aQNMaqMgRtv+BJBJrp4ktyQDKK0b2449BXChI0JB5d9397IJ5egk3H4Hz+KByaKe4C 3uxVLjqGR8OKpM3iF+el8OwBF/ZZHZcsTa4PMww+LWuD7HEhlQ7znoXw6hKgiHYNruABzPcZ3OUIw g9h0DMBQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t3Tn6-0000000D1wl-28rt; Wed, 23 Oct 2024 05:20:16 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t3TmC-0000000D1nj-3Ioz for linux-nvme@lists.infradead.org; Wed, 23 Oct 2024 05:19:22 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 9AB31227A87; Wed, 23 Oct 2024 07:19:15 +0200 (CEST) Date: Wed, 23 Oct 2024 07:19:15 +0200 From: Christoph Hellwig To: Sagi Grimberg Cc: Ming Lei , zhuxiaohui , axboe@kernel.dk, kbusch@kernel.org, hch@lst.de, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, Zhu Xiaohui Subject: Re: [PATCH v1] blk-mq: add one blk_mq_req_flags_t type to support mq ctx fallback Message-ID: <20241023051914.GA1341@lst.de> References: <20241020144041.15953-1-zhuxiaohui.400@bytedance.com> <064a6fb0-0cdb-4634-863d-a06574fcc0fa@grimberg.me> <6edb988e-2ec0-49b4-b859-e8346137ba68@grimberg.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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-20241022_221920_992933_3F9ABC58 X-CRM114-Status: GOOD ( 16.72 ) 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 Tue, Oct 22, 2024 at 04:23:29PM +0300, Sagi Grimberg wrote: > I agree. NVMe may have a unique need here, but it needs a tag from a > specific hctx while the context requesting it does not map according to > the hctx cpumap. It cannot use any other tag from any other hctx. > > The reason is that the connect for a queue must be done from a tag that > belongs to the queue because nvme relies on it when it does resolution back > to > the request to the completion. I wonder if we should byte the bullet and not use a request for the connect commands. We've already special cased the AEN command because it was causing too many problems, and given all the pain so far connect might also have hit that treshold.