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 AC419C43334 for ; Wed, 6 Jul 2022 16:34:49 +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=Dlq6ocRju/wsf2zkNUuYJY8keBab9BeuCt8KMsYue7U=; b=oFImC8X8KaDpYh/qfi0zEuABQG E7CFtMdMFDeJq+ezgDIaQH9wy8f/q5Bcx5EOuWew32oJqpJLGeHWJ37rfz662tQTvkcO5JvS6JBwF ArVqsCsW2iHMqrRmQQYLBvO9gSXosuvgMcFz8OknewyG0bYKieasWANaQjtJB5o7TflZlzjUSzpBj OSfFcNsYsju2WV3i/dHYVyhuIHubGQvWgi27rP2QsuTsouw2Rfy7Uzdn9XVDF+5BZpb19rm4caEo4 sv5Y2LxWJm2ZS0FCy6fGiUZRc3MbuGjANXRUi54skcBnk8Hn3jNCLv0zSTK4wCXXEqlEuPl/3O55J tGBkDF2g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o97z9-00BNxn-6F; Wed, 06 Jul 2022 16:34:43 +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 1o97z5-00BNw4-BT for linux-nvme@lists.infradead.org; Wed, 06 Jul 2022 16:34:41 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id ABB1E68BEB; Wed, 6 Jul 2022 18:34:34 +0200 (CEST) Date: Wed, 6 Jul 2022 18:34:34 +0200 From: Christoph Hellwig To: Keith Busch Cc: Christoph Hellwig , John Garry , axboe@fb.com, sagi@grimberg.me, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] nvme: Fix nvme_setup_command metadata trace event for cdw10 Message-ID: <20220706163434.GA2222@lst.de> References: <1657095398-114310-1-git-send-email-john.garry@huawei.com> <20220706161825.GA1962@lst.de> 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-20220706_093439_587000_15C9B2C9 X-CRM114-Status: GOOD ( 22.52 ) 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 Wed, Jul 06, 2022 at 10:26:09AM -0600, Keith Busch wrote: > On Wed, Jul 06, 2022 at 06:18:25PM +0200, Christoph Hellwig wrote: > > On Wed, Jul 06, 2022 at 10:13:22AM -0600, Keith Busch wrote: > > > Did you test what the trace looks like afte this? We're losing valuable trace > > > data here. The field is supposed to get CDW's 10 - 15, so that's 24 bytes. I > > > don't know why it cares that the address of the field being read is only 4 > > > bytes; we want everything that comes after it too. > > > > Because accesses should not spawn boundaries of members in structs unless > > copying the entire struct. If we want to trace the various fields we > > need to individually assign them. > > > > Anyway, I'm dropping this patch from nvme-5.19 for now to let the > > discussion conclude. > > How about this instead? Maybe a better option would be to use struct_group().