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 6B2D37346D; Fri, 15 Nov 2024 23:14:30 +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=1731712470; cv=none; b=TBKjQtfA9nV7uN1WIs6Qeta6uxQKVuwIPh1gBZ5pT6DW3jp3pHk+qX5NszJCol9YU4M/PN8xqWKzfXoapjUlSD4qjXEvfdx2BjW5KQR3FC6neZdgusKx9T+lH9Sdd40gd37+/34N4FqcF3wXzR5P6Q5Z9Od0+wmapSq03trwNf4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731712470; c=relaxed/simple; bh=J1PCIr/PU/DXaWzOtmgtsPvaZQwvafBBPKoR46EfPcg=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=txEgYgRaL/ShfneDwvl5LGDkv8YQP7S8QONyDskOy/gGCq9dJ6mavDdkpv7D1IYKnXvXx/P1ZuBJPKbUTLvVtnXLX/Zn3K6JyniBUtVLx4Pt7klcMsMqFlrKohuFNGWPQTOO/C1FbitsGqevElaWA+xR0rxy/XNzh1+BKgiLUF0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BwrObFAi; 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="BwrObFAi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7363EC4CECF; Fri, 15 Nov 2024 23:14:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731712469; bh=J1PCIr/PU/DXaWzOtmgtsPvaZQwvafBBPKoR46EfPcg=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=BwrObFAieGavwTj03Tqnx2NrxNzFDbvP7p7kzo9PEG6foBBkkiDolALWhrPI8Pa+1 ji0004+YMYdq/VVxSZOvCbpi8/BShNdmIN7TFa/uv9ab7cE06utouqFxUhg+rhTBEL q9uVIEoiX2Ti3q6BcsFe8kWoP0SrgcucfSfMGzoYliHF8MIw7OlGK+WrQw81Wdhqkx SuR1YB/5cHX+9Z1S5PPaBRfK25mPeT4/ykwSMLpBEkbZljUUzm3ghuHeZCaJJB6Xe0 YWzWAT5q5YbNzHeSSDN6wmncbME88iR7ZfweDU1WkZRZBq/TyIsuGQhPnUBRcYZvmi 9fyu1JGKQ6ygA== Date: Fri, 15 Nov 2024 15:14:28 -0800 From: Jakub Kicinski To: Mina Almasry Cc: David Wei , Pavel Begunkov , io-uring@vger.kernel.org, netdev@vger.kernel.org, Jens Axboe , Paolo Abeni , "David S. Miller" , Eric Dumazet , Jesper Dangaard Brouer , David Ahern , Stanislav Fomichev , Joe Damato , Pedro Tammela Subject: Re: [PATCH v7 11/15] io_uring/zcrx: implement zerocopy receive pp memory provider Message-ID: <20241115151428.6f1e1aba@kernel.org> In-Reply-To: References: <20241029230521.2385749-1-dw@davidwei.uk> <20241029230521.2385749-12-dw@davidwei.uk> <9ed60db4-234c-4565-93d6-4dac6b4e4e15@davidwei.uk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 14 Nov 2024 12:56:14 -0800 Mina Almasry wrote: > But I've been bringing this up a lot in the past (and offering > alternatives that don't introduce this overloading) and I think this > conversation has run its course. I'm unsure about this approach and > this could use another pair of eyes. Jakub, sorry to bother you but > you probably are the one that reviewed the whole net_iov stuff most > closely. Any chance you would take a look and provide direction here? > Maybe my concern is overblown... Sorry I haven't read this code very closely (still!?) really hoping=20 for next version to come during the merge window when time is more abundant :S =46rom scanning the quoted context I gather you're asking about using=20 the elevated ->pp_ref_count for user-owned pages? If yes - I also find that part.. borderline incorrect. The page pool stats will show these pages as allocated which normally means held by the driver or=20 the stack. Pages given to the user should effectively leave the pool. So I'm guessing this is some optimization. Same for patch 8. But let me not get sucked into this before we wrap up the net-next PR..