From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 9712026560D; Thu, 8 Jan 2026 16:33:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767890030; cv=none; b=I77AXDgw93x4SGmz0z5h8Ad8AOHtkR+ER2p/rCLKKChpQXoxlaCqhLzdA47VKkVg9z3mwS6WbbbGTkvorpuIXW22SmgL2BaH1ZNZNtK5W+4AP9aNQI1a/vUlU/5vf0RbJdaydOJY5yOZDFCYb1LzHRaNAubHutXgJh8DLLyqpbM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767890030; c=relaxed/simple; bh=AGZNwDpQqmCuS0ZembsvxsxGBegKk8NFWbTC37qZICc=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=IWN85CXK5MkihAN+q/nB9p9Vbxyh17z830vzO3gQ7z9P7qnb9inOEHrrlwSy7rnD9bLXj0k6fTF3QP88eVbCMbtEKffZ76JpbzcjWuONp9RlJn4ZlmA3Qh6Ixh3/f+H9teSSybyLHecISFJ+BSyLYe8AGrGpCQ0tzsL7okDWrGg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=desiato.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=hUtEYCw3; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=desiato.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="hUtEYCw3" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=g8c5uFLop3/jlRNNx8JcaFswrG8Sx8WRDiJjznTPOag=; b=hUtEYCw3CM/puZ7Yote1TTXoB1 xzCYTks/1nTe1OO//2zJ2G+5c5gZaHcSvR6hynMQXYMqyUfIwFWrvFBIy2m2rv7Zy9r2aMdKlqwc3 hUKH5dhRixs1i6zYqD4zyCPQXefUnyxaQz77zWefL/wG63iJ91jpPKYIhckBq/I3LHPFRnuvc+a/I YS65/g9VBoitFNElOEkMSlNic2N69UHgQyX06PTQ1wjv8HSWNxRFkLPWDuM3sG8OFeByBSaqhRpRu SBCqUSfgZIJmKFoBZ3RVxzPBZFQ5ib81XiQbviZLV+mv6SeQrI7AKPEeqLo9LNUGyhymscLNQxoJU zyvFA1wQ==; Received: from [149.13.74.102] (helo=u09cd745991455d.ant.amazon.com) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vdsxE-0000000Dfep-0n42; Thu, 08 Jan 2026 16:33:44 +0000 Message-ID: Subject: Re: [PATCH v4 4/9] vsock/virtio: Resize receive buffers so that each SKB fits in a 4K page From: David Woodhouse To: Will Deacon , linux-kernel@vger.kernel.org Cc: Keir Fraser , Steven Moreland , Frederick Mayle , Stefan Hajnoczi , Stefano Garzarella , "Michael S. Tsirkin" , Jason Wang , Eugenio =?ISO-8859-1?Q?P=E9rez?= , netdev@vger.kernel.org, virtualization@lists.linux.dev Date: Thu, 08 Jan 2026 17:33:42 +0100 In-Reply-To: <20250717090116.11987-5-will@kernel.org> References: <20250717090116.11987-1-will@kernel.org> <20250717090116.11987-5-will@kernel.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-ht17kk5Y4zMafZO0ELKM" User-Agent: Evolution 3.52.3-0ubuntu1.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html --=-ht17kk5Y4zMafZO0ELKM Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2025-07-17 at 10:01 +0100, Will Deacon wrote: >=20 > -#define VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE (1024 * 4) > +/* Dimension the RX SKB so that the entire thing fits exactly into > + * a single 4KiB page. This avoids wasting memory due to alloc_skb() > + * rounding up to the next page order and also means that we > + * don't leave higher-order pages sitting around in the RX queue. > + */ > +#define > VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE SKB_WITH_OVERHEAD(1024 * 4) Should this be SKB_WITH_OVERHEAD()? Or should it subtract VIRTIO_VSOCK_SKB_HEADROOM instead? (And also, I have use cases where I want to expand this to 64KiB. 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