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 AEAECCA6007 for ; Thu, 8 Oct 2026 12:37:40 +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=D8oaLiBOeyXnutecsSkzdwdFr9Xa2ksmNjevdN2sBjQ=; b=5D+OonSLy+ihqjJgLwRbNBIdvC KxWfUwdOifXsrdyTBAcCVC25h5X1VfaYZ8Itg7XJj0xZsz4sCHkOBHcEFP/93P1f/4rdYCEpiAfLK P/S7nA7r7an43JcFn2sXp2PBpA93UqemDX3kj6pFAph4GAn4EHwQc4Z+0k2IF0keWKYsg2f1CqcSl EnFzKhC4QdjQduwyhyC2oT5XBb/nIwCgtKXXd5IaZy8l+TAwgf54E4E+UaaaUBeseW+krsg/bJW6N EyT3KkinhE6Pk4UTv7/dHSObeKsgl1x5zr8z+6UX9UKERFoxFNp1/841BmMwfsU+nYdlgqf4OmWiw p/Wtq1Cg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xEnNS-00000004NNq-372F; Thu, 08 Oct 2026 12:37:38 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xEnNO-00000004NND-3k4O for linux-nvme@lists.infradead.org; Thu, 08 Oct 2026 12:37:36 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 0909668BEB; Thu, 8 Oct 2026 14:37:25 +0200 (CEST) Date: Thu, 8 Oct 2026 14:37:24 +0200 From: Christoph Hellwig To: John Garry Cc: Christoph Hellwig , kbusch@kernel.org, ahuang12@lenovo.com, sagi@grimberg.me, linux-nvme@lists.infradead.org, sunjw10@lenovo.com, iommu@lists.linux.dev Subject: Re: [PATCH] Revert "nvme-pci: clamp max_hw_sectors based on DMA optimized limitation" Message-ID: <20261008123724.GA22096@lst.de> References: <20261006120248.147654-1-hch@lst.de> <8cf8a8ea-c9c9-434b-aec6-e361280a88a4@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8cf8a8ea-c9c9-434b-aec6-e361280a88a4@linux.dev> User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261008_053735_105609_CB3276DE X-CRM114-Status: GOOD ( 12.77 ) 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 Thu, Oct 08, 2026 at 08:36:54AM +0100, John Garry wrote: > On 10/6/26 13:02, Christoph Hellwig wrote: >> This turns down to cause up to 15% performance regressions on standard >> large transfer workloads. Revert it and hope the IOVA allocator can >> eventually be fixed to remove the need for the original workaround. >> >> This reverts commit 3710e2b056cb92ad816e4d79fa54a6a5b6ad8cbd. >> > > What was the block size and conditions for the original issue? The commit > just mentions that mdts=10 and we get a 4096KB max HW sectors. Good question. The original submitter and reporter are on Cc.