From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: [PATCH V2] xen/netfront: improve truesize tracking Date: Mon, 7 Jan 2013 15:32:06 +0000 Message-ID: <1357572726-7059-1-git-send-email-ian.campbell@citrix.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Ian Campbell , Sander Eikelenboom , Konrad Rzeszutek Wilk , annie li , To: Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:60795 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753068Ab3AGPcI (ORCPT ); Mon, 7 Jan 2013 10:32:08 -0500 Sender: netdev-owner@vger.kernel.org List-ID: 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 Cc: stable@kernel.org # 3.7.x only --- v2: - acount frags as a full page as recommended by Eric. --- drivers/net/xen-netfront.c | 27 ++++----------------------- 1 files changed, 4 insertions(+), 23 deletions(-) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index caa0110..b518538 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -959,29 +959,10 @@ 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) -- 1.7.2.5