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 64061CA6019 for ; Fri, 9 Oct 2026 15:37:24 +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=kLgpLQENCeXHMZ4r/LduUsI/Qb8wWOkpqbiHZFcOMxE=; b=Dn3WHHw4Kr4MQtAJupBQo/C93Y 2Mb2hNbYK4qG8yh452i8ahnCtg6Fx2IcyfHuUAW2TMimWtvMir/987dGTeF+9vzK/xr4XKLSW4J6T wqZ8U0E2HEJ1HzYNJ6as4mqSw0AJd8FC615dZQid8Stg/lfRyvN9djiQJupSDeE1Nm5T4OElMZ0/R JDcRvv/hjXMcGwmgCGFyPjWFN3S0UiwtJYTkKSsWFkPQbRMEDriAEkSTXRnMQtTIHCm6EpJyOh9Vw Q0OB2GFyJ7eCoLfC0slNADoEs1jyQfN2c6Nv6IzZ/huqFb/Q13J641zRAoQnLCDSz6b98zaltQmiS cg7mif/w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xFCew-00000006XzI-45Gz; Fri, 09 Oct 2026 15:37:22 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xFCev-00000006Xyu-16tA for linux-nvme@lists.infradead.org; Fri, 09 Oct 2026 15:37:21 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 9AFB760098; Fri, 9 Oct 2026 15:37:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DB7E61F000FF; Fri, 9 Oct 2026 15:37:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791560240; bh=kLgpLQENCeXHMZ4r/LduUsI/Qb8wWOkpqbiHZFcOMxE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=VJ8jwhPtr5b0JPDRMAC0FHI1wuMC/MGaiRyKN1N8/ndV1HO6Q6ox8I3kOCbjBTBML keOQ9pfgaIKn6fIOxv66OSyD7YK/CnmLrEKHz39U6MX2ZI757rKIgjRPXDXr1Qygrx o2vbODyY9paPenMBASgTCI6bO1AwvxZv9uP6i32D+EUHhzhYqqeHGEgOKOxc9nP3cM fe8ZKif+f9EolQEU6W+0NBiLB9mRXaIox9U73wnowSa9h3ddYsPWtA+9WJgJ/58Lju 6MIRyv9kMa4yqBcCx6dJKhBDPCUdvzcEOoL01wNtKmqxsDxjOTeP8WcUG4lI7ixv/z xrx+WQr9VJcsw== Date: Fri, 9 Oct 2026 09:37:18 -0600 From: Keith Busch To: Adrian Huang12 Cc: Christoph Hellwig , John Garry , "sagi@grimberg.me" , "linux-nvme@lists.infradead.org" , Jiwei JW10 Sun , "iommu@lists.linux.dev" Subject: Re: [External] Re: [PATCH] Revert "nvme-pci: clamp max_hw_sectors based on DMA optimized limitation" Message-ID: References: <20261006120248.147654-1-hch@lst.de> <8cf8a8ea-c9c9-434b-aec6-e361280a88a4@linux.dev> <20261008123724.GA22096@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Fri, Oct 09, 2026 at 09:11:56AM +0000, Adrian Huang12 wrote: > > BTW, with this reverted patch, I'm setting up the test environment to > check whether the issue does not appear with a newer kernel that > includes the updated IOMMU subsystem. I'll share the results by the > end of next week. It does sound like an IOMMU implementation issue if the revert regresses your testing. Let's say the application wants to write 1MB of data: we're DMA mapping the same total amount either way, so I don't think it should have been more efficient for the driver to send eight 128k mapping requests vs a single 1MB.