* [PATCH] IPoIB: fix skb truesize underestimatiom
@ 2012-07-10 20:03 Eric Dumazet
2012-07-11 6:37 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: Eric Dumazet @ 2012-07-10 20:03 UTC (permalink / raw)
To: David Miller
Cc: Or Gerlitz, Erez Shitrit, Roland Dreier, netdev, Shlomo Pongartz
From: Eric Dumazet <edumazet@google.com>
Or Gerlitz reported triggering of WARN_ON_ONCE(delta < len); in
skb_try_coalesce()
This warning tracks drivers that incorrectly set skb->truesize
IPoIB indeed allocates a full page to store a fragment, but only
accounts in skb->truesize the used part of the page (frame length)
This patch fixes skb truesize underestimation, and
also fixes a performance issue, because RX skbs have not enough tailroom
to allow IP and TCP stacks to pull their header in skb linear part
without an expensive call to pskb_expand_head()
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Or Gerlitz <ogerlitz@mellanox.com>
Cc: Erez Shitrit <erezsh@mellanox.com>
Cc: Shlomo Pongartz <shlomop@mellanox.com>
Cc: Roland Dreier <roland@purestorage.com>
---
drivers/infiniband/ulp/ipoib/ipoib_ib.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index 5c1bc99..f10221f 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -123,7 +123,7 @@ static void ipoib_ud_skb_put_frags(struct ipoib_dev_priv *priv,
skb_frag_size_set(frag, size);
skb->data_len += size;
- skb->truesize += size;
+ skb->truesize += PAGE_SIZE;
} else
skb_put(skb, length);
@@ -156,14 +156,18 @@ static struct sk_buff *ipoib_alloc_rx_skb(struct net_device *dev, int id)
struct ipoib_dev_priv *priv = netdev_priv(dev);
struct sk_buff *skb;
int buf_size;
+ int tailroom;
u64 *mapping;
- if (ipoib_ud_need_sg(priv->max_ib_mtu))
+ if (ipoib_ud_need_sg(priv->max_ib_mtu)) {
buf_size = IPOIB_UD_HEAD_SIZE;
- else
+ tailroom = 128; /* reserve some tailroom for IP/TCP headers */
+ } else {
buf_size = IPOIB_UD_BUF_SIZE(priv->max_ib_mtu);
+ tailroom = 0;
+ }
- skb = dev_alloc_skb(buf_size + 4);
+ skb = dev_alloc_skb(buf_size + tailroom + 4);
if (unlikely(!skb))
return NULL;
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] IPoIB: fix skb truesize underestimatiom
2012-07-10 20:03 [PATCH] IPoIB: fix skb truesize underestimatiom Eric Dumazet
@ 2012-07-11 6:37 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2012-07-11 6:37 UTC (permalink / raw)
To: eric.dumazet; +Cc: ogerlitz, erezsh, roland, netdev, shlomop
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 10 Jul 2012 22:03:41 +0200
> From: Eric Dumazet <edumazet@google.com>
>
> Or Gerlitz reported triggering of WARN_ON_ONCE(delta < len); in
> skb_try_coalesce()
> This warning tracks drivers that incorrectly set skb->truesize
>
> IPoIB indeed allocates a full page to store a fragment, but only
> accounts in skb->truesize the used part of the page (frame length)
>
> This patch fixes skb truesize underestimation, and
> also fixes a performance issue, because RX skbs have not enough tailroom
> to allow IP and TCP stacks to pull their header in skb linear part
> without an expensive call to pskb_expand_head()
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: Or Gerlitz <ogerlitz@mellanox.com>
Applied to net, thanks.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2012-07-10 20:03 [PATCH] IPoIB: fix skb truesize underestimatiom Eric Dumazet
2012-07-11 6:37 ` David Miller
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