From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0EBD625D8E4 for ; Tue, 20 May 2025 09:16:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747732603; cv=none; b=RfsfbAEgRSEzL9nkCXN0phpF7Y0nNEeBSq6fzxfTv7A2NtV9VrMgJFenO1T5w20nYaNa6vrUm1/kD/I42G/QGRmK6BtLSle5eIUauhP+OQqi2JwuxnvIF/orvaIavvKJJU0XDS6nwejqkRy53GHJaZiAQRl07uiVZXhkWKxYsZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747732603; c=relaxed/simple; bh=0IyP0W/nyym4onsH5sTTxS+N0cmP4rLgTKZYMCTLHFE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=uNRYb0P5kmnmp3lwhGD0VFx9oXJhcFMRB1iDqo53U4xRf+WJbj/l8t1LmxTBem/dOFWkzMkIV5bGJU7cqZYSwP07GSOIMFe6qFSUVHh4/hXAmyrRVLPxWrgUt1lnPFTBjxx3L55OM7xQPw+nMzz3ientONcv0LuJxl1y1NiMoEM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=XMOfEWVA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="XMOfEWVA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E636DC4CEEB; Tue, 20 May 2025 09:16:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747732602; bh=0IyP0W/nyym4onsH5sTTxS+N0cmP4rLgTKZYMCTLHFE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XMOfEWVAf11esiGLlz/eVSN5GLQvZC0y/mSv8JXvdNbM6lf2ox8rO+PPv0HP5QI09 ZLiScXFuCGDOBxrYDAEy6gEzDf98WVvEBVqaDmw9QKSUYusXwbJjU/BmsaBWU+tQfs tE80pcGliMUevoTDLs5VH8E8TUrpNrg9itvNGhSuGtAZe16+Eh6JsSl8h06GPl1zhP ZljpDcXHhLhQpzD7MoYwrDg/1EXYRUxtNYnHtMFvDK6HlCkL61otXHLX9SXkt0l5hh j0eyiCt5qR44CnKCQRuuZkKxqbP4OKKt6A9qNDoIiYoB3te/4IA4CIKATQVEdoLLac xHeIePnpfjjMQ== Date: Tue, 20 May 2025 12:16:38 +0300 From: Leon Romanovsky To: "Margolin, Michael" Cc: jgg@nvidia.com, linux-rdma@vger.kernel.org, sleybo@amazon.com, matua@amazon.com, gal.pressman@linux.dev, Daniel Kranzdorf , Yonatan Nachum Subject: Re: [PATCH for-next] RDMA/efa: Add CQ with external memory support Message-ID: <20250520091638.GF7435@unreal> References: <20250515145040.6862-1-mrgolin@amazon.com> <20250518064241.GC7435@unreal> <985b77cc-63bb-4cf9-885e-c2d6aca95551@amazon.com> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <985b77cc-63bb-4cf9-885e-c2d6aca95551@amazon.com> On Sun, May 18, 2025 at 11:56:56AM +0300, Margolin, Michael wrote: > > On 5/18/2025 9:42 AM, Leon Romanovsky wrote: > > CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you can confirm the sender and know the content is safe. > > > > > > > > On Thu, May 15, 2025 at 02:50:40PM +0000, Michael Margolin wrote: > > > Add an option to create CQ using external memory instead of allocating > > > in the driver. The memory can be passed from userspace by dmabuf fd and > > > an offset. > > EFA is unique here. This patch is missing description of why it is > > needed, and why existing solutions if any exist, can't be used. > > > > Thanks > > I probably should have explained more, the purpose is creating CQs that > reside in GPU HBM enabling low latency polling directly by the GPU. EFA > isn't unique in receiving pre-allocated memory from userspace, the extension > here is the use of dmabuf for that purpose as a general mechanism that > allows using memory independent of its source. I will add more info in the > commit message. I think that this functionality is worth to have as general verb and not DV. mlx5 has something similar and now EFA needs it too. Let's wait for Jason's response before rushing to implement it. Thanks > > Michael >