From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailout4.samsung.com (mailout4.samsung.com [203.254.224.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 81159371075 for ; Wed, 4 Feb 2026 06:07:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=203.254.224.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770185256; cv=none; b=uXgdETzvBSELtBznLs+MZQ0t7Lhhk7blx5nxBqu0y+YHL/mIdqW9TDYySVuabi3iUeyQcZt06KKsXvf3o1BojKZVB8CFYz0Xg8sJv3jEWh0rfxKycb+a7atvqwT03Boo1EGOeA8zyr6fpTXW4Qsi8l33U5O8VXHsGYk+sSCvA3U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770185256; c=relaxed/simple; bh=vFeASoXmH/a8+nINHgGsmh6ICV7WwiJIChiSbgDwE7s=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:From:In-Reply-To: Content-Type:References; b=ATkzQpdUoXqqpeneraggPP37Z4zH7l08N+vTbiwpOO+qGsTnLzLy/TgKXGWl9wEBPZVxJDRU4W+UEcWK017IfilyL6/zwII5o0TZCjjt8uHjMTUupR0W0v2aJ3xEXABBgEaU77SnLTwQI/TD2abwgq46Nl2jFPRwPDqU7pEc3VQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com; spf=pass smtp.mailfrom=samsung.com; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b=NhzBjLSH; arc=none smtp.client-ip=203.254.224.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=samsung.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=samsung.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="NhzBjLSH" Received: from epcas5p2.samsung.com (unknown [182.195.41.40]) by mailout4.samsung.com (KnoxPortal) with ESMTP id 20260204060727epoutp04e9618116949734219eac3e9f18945bb1~Q9hqnTUpa0200002000epoutp04E for ; Wed, 4 Feb 2026 06:07:27 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout4.samsung.com 20260204060727epoutp04e9618116949734219eac3e9f18945bb1~Q9hqnTUpa0200002000epoutp04E DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1770185247; bh=y2frTBlrPcApGJAKcojyrODxcLgxJHU1QEnp9KWJoZE=; h=Date:Subject:To:Cc:From:In-Reply-To:References:From; b=NhzBjLSHtZQSQfwpotD0ry+Zimlaaw5fqm639OJbdbhO5fR5z5AnqlhFlOCe902o8 frZCx7w8qfrbc9ahl5e4C1eLYZNUptEigCQ8ZEOyCMxJPQOOiJ1ezeBjZ7cSv9MUPd pWrdY+SkrHWCbDZFh9P9kvzipTxVl2Dyw8JReVZ8= Received: from epsnrtp02.localdomain (unknown [182.195.42.154]) by epcas5p2.samsung.com (KnoxPortal) with ESMTPS id 20260204060727epcas5p232ff332ff546f37733e37b0c13d6cada~Q9hqaEc0W0625406254epcas5p2u; Wed, 4 Feb 2026 06:07:27 +0000 (GMT) Received: from epcas5p4.samsung.com (unknown [182.195.38.94]) by epsnrtp02.localdomain (Postfix) with ESMTP id 4f5VHy44lQz2SSKd; Wed, 4 Feb 2026 06:07:26 +0000 (GMT) Received: from epsmtip2.samsung.com (unknown [182.195.34.31]) by epcas5p3.samsung.com (KnoxPortal) with ESMTPA id 20260204060726epcas5p3816adfde071ae343471ac7a6a33a0e82~Q9ho7YiaV1775217752epcas5p3N; Wed, 4 Feb 2026 06:07:26 +0000 (GMT) Received: from [107.122.10.194] (unknown [107.122.10.194]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20260204060722epsmtip24e8143a262629db8288b2256b0e51ace~Q9hlWsA3n1083210832epsmtip2D; Wed, 4 Feb 2026 06:07:22 +0000 (GMT) Message-ID: Date: Wed, 4 Feb 2026 11:37:20 +0530 Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM/BPF TOPIC] dmabuf backed read/write To: Keith Busch , Pavel Begunkov Cc: linux-block@vger.kernel.org, io-uring , "linux-nvme@lists.infradead.org" , =?UTF-8?Q?Christian_K=C3=B6nig?= , Christoph Hellwig , Kanchan Joshi , Nitesh Shetty , "lsf-pc@lists.linux-foundation.org" Content-Language: en-US From: Anuj Gupta/Anuj Gupta In-Reply-To: Content-Transfer-Encoding: 8bit X-CMS-MailID: 20260204060726epcas5p3816adfde071ae343471ac7a6a33a0e82 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 105P cpgsPolicy: CPGSC10-542,Y X-CFilter-Loop: Reflected X-CMS-RootMailID: 20260203180716epcas5p1c9658e583e26197b515f6db07a100aa9 References: <4796d2f7-5300-4884-bd2e-3fcc7fdd7cea@gmail.com> On 2/3/2026 11:37 PM, Keith Busch wrote: > Thanks for submitting the topic. The performance wins look great, but > I'm a little surpised passthrough didn't show any difference. We're > still skipping a bit of transformations with the dmabuf compared to not > having it, so maybe it's just a matter of crafting the right benchmark > to show the benefit. > Those numbers were from a drive that saturates at ~5M IOPS, sopassthrough didn’t have much headroom. I did a quick run with two such drives and saw a small improvement (~2–3%): ~5.97 MIOPS -> ~6.13 MIOPS, but I’ll try tweaking the kernel config a bit to see if there’s more headroom. +1 on the topic - I'm interested in attending the discussion and reviewing/testing v3 when it lands. Thanks, Anuj