From mboxrd@z Thu Jan 1 00:00:00 1970 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.subspace.kernel.org (Postfix) with ESMTPS id CF67972605; Tue, 3 Jun 2025 16:02:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748966531; cv=none; b=i7FrN8rM9ESqiplNlWKC0ZqKlKomb3T+jnAA7OAM1zvwOWey9NfDgUH/Ty4wPwSLR5y1Q76LG+KnBIpktfBpjWyfBuQv3W/q0ObsisxTV8RJ9yAqQv9RRgHZWitdrNAYQxlhmUxYG1QeyJ62w/J6Fhn+QItabMb8hDk05zKjgM4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748966531; c=relaxed/simple; bh=utGGHye6zuMyX2IqEOVmv3+Md9E7v87JO8RTvtptp4w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WiHDy98mmW+haaLt4hlR3krye0GUsmDuxIeYlyntyTdV69OZBMPPWu37M/z6KQT2ajzOSEWvz2Xhb0RCoKgqkmiY+PAniyZ5Abu5yd0bQibT/l0tbGrVMFPHMu/64UXAFedTSODj83WVIfXDTVunvbbkB5fiPLbcglCnwodC118= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=OluYoGGV; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="OluYoGGV" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=lqpA2obXAEGYiV7llfEv48yhrGfp0onTICfwh/ANc24=; b=OluYoGGVKqLlm6rzxdjM4LhMQ1 eOPz3SupE+Bw9ysysO+kM/cAgvP06gWwIbzC4/e4gASjwVugANssBjc40YPUGAx+Pj/cmjG3+82q5 ArJv2MFY9l9APkjyj+Yoq3yRmcH4NTq6C8N7+2xDqz76XDB+kn3u2iRial5JhXnskyYxuwaozZLDK 86nULefboRLcSVdt6e0PZk4PZPJNI/v2PdtKLZ9GxYdJtdmt/bXzjlJ5pPNkX0MbOyih2PJE2o/JN 5iAGN7D8oW5lzjB+iOXUn0QOl0bteQbmcnNIdnGqC+cRk6GyHKpthYQeF10F4Y/qlSP7eOdt5Vl6m oPf9mjfw==; Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uMU5P-0000000BMWf-1H2s; Tue, 03 Jun 2025 16:01:59 +0000 Date: Tue, 3 Jun 2025 09:01:59 -0700 From: Christoph Hellwig To: Christian =?iso-8859-1?Q?K=F6nig?= Cc: Christoph Hellwig , wangtao , sumit.semwal@linaro.org, kraxel@redhat.com, vivek.kasireddy@intel.com, viro@zeniv.linux.org.uk, brauner@kernel.org, hughd@google.com, akpm@linux-foundation.org, amir73il@gmail.com, benjamin.gaignard@collabora.com, Brian.Starkey@arm.com, jstultz@google.com, tjmercier@google.com, jack@suse.cz, baolin.wang@linux.alibaba.com, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, bintian.wang@honor.com, yipengxiang@honor.com, liulu.liu@honor.com, feng.han@honor.com Subject: Re: [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range Message-ID: References: <20250603095245.17478-1-tao.wangtao@honor.com> <09c8fb7c-a337-4813-9f44-3a538c4ee8b1@amd.com> <924ac01f-b86b-4a03-b563-878fa7736712@amd.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Tue, Jun 03, 2025 at 05:55:18PM +0200, Christian König wrote: > On 6/3/25 16:28, Christoph Hellwig wrote: > > On Tue, Jun 03, 2025 at 04:18:22PM +0200, Christian König wrote: > >>> Does it matter compared to the I/O in this case? > >> > >> It unfortunately does, see the numbers on patch 3 and 4. > > > > That's kinda weird. Why does the page table lookup tage so much > > time compared to normal I/O? > > I have absolutely no idea. It's rather surprising for me as well. > > The user seems to have a rather slow CPU paired with fast I/O, but it still looks rather fishy to me. > > Additional to that allocating memory through memfd_create() is *much* slower on that box than through dma-buf-heaps (which basically just uses GFP and an array). Can someone try to reproduce these results on a normal system before we're building infrastructure based on these numbers?