From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [ 103/221] xen/netfront: improve truesize tracking Date: Tue, 15 Jan 2013 10:50:30 -0800 Message-ID: <20130115185005.470007939@linuxfoundation.org> References: <20130115184958.025580322@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20130115184958.025580322@linuxfoundation.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Ian Campbell , Konrad Rzeszutek Wilk , Greg Kroah-Hartman , Eric Dumazet , xen-devel@lists.xen.org, Sander Eikelenboom , annie li , netdev@vger.kernel.org, "David S. Miller" , alan@lxorguk.ukuu.org.uk List-Id: xen-devel@lists.xenproject.org 3.7-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ian Campbell commit d9a58a782e396a0f04e8445b7ba3763c8a48c7fe upstream. Using RX_COPY_THRESHOLD is incorrect if the SKB is actually smaller than that. We have already accounted for this in NETFRONT_SKB_CB(skb)->pull_to so use that instead. Fixes WARN_ON from skb_try_coalesce. Signed-off-by: Ian Campbell Cc: Sander Eikelenboom Cc: Konrad Rzeszutek Wilk Cc: annie li Cc: xen-devel@lists.xen.org Cc: netdev@vger.kernel.org Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netfront.c | 27 ++++----------------------- 1 file changed, 4 insertions(+), 23 deletions(-) --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -1015,29 +1015,10 @@ err: i = xennet_fill_frags(np, skb, &tmpq); /* - * Truesize approximates the size of true data plus - * any supervisor overheads. Adding hypervisor - * overheads has been shown to significantly reduce - * achievable bandwidth with the default receive - * buffer size. It is therefore not wise to account - * for it here. - * - * After alloc_skb(RX_COPY_THRESHOLD), truesize is set - * to RX_COPY_THRESHOLD + the supervisor - * overheads. Here, we add the size of the data pulled - * in xennet_fill_frags(). - * - * We also adjust for any unused space in the main - * data area by subtracting (RX_COPY_THRESHOLD - - * len). This is especially important with drivers - * which split incoming packets into header and data, - * using only 66 bytes of the main data area (see the - * e1000 driver for example.) On such systems, - * without this last adjustement, our achievable - * receive throughout using the standard receive - * buffer size was cut by 25%(!!!). - */ - skb->truesize += skb->data_len - RX_COPY_THRESHOLD; + * Truesize is the actual allocation size, even if the + * allocation is only partially used. + */ + skb->truesize += PAGE_SIZE * skb_shinfo(skb)->nr_frags; skb->len += skb->data_len; if (rx->flags & XEN_NETRXF_csum_blank)