From: Roland Dreier <rol...@purestorage.com>
Markus Stockhausen <markus.stockhau...@gmx.de> noticed that IPoIB was
spending significant time doing memcpy() in __pskb_pull_tail(). He
found that this is because his adapter reports a maximum MTU of 4K,
which causes IPoIB datagram mode to receive all the actual data in a
separate page in the fragment list.
We're already allocating extra tailroom for the skb linear part, so we
might as well use it.
Cc: Eric Dumazet <eduma...@google.com>
Reported-by: Markus Stockhausen <markus.stockhau...@gmx.de>
Signed-off-by: Roland Dreier <rol...@purestorage.com>
---
drivers/infiniband/ulp/ipoib/ipoib.h | 3 ++-
drivers/infiniband/ulp/ipoib/ipoib_ib.c | 12 +++---------
2 files changed, 5 insertions(+), 10 deletions(-)
diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h
b/drivers/infiniband/ulp/ipoib/ipoib.h
index eb71aaa..ab2cc4c 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -64,7 +64,8 @@ enum ipoib_flush_level {
enum {
IPOIB_ENCAP_LEN = 4,
- IPOIB_UD_HEAD_SIZE = IB_GRH_BYTES + IPOIB_ENCAP_LEN,
+ /* add 128 bytes of tailroom for IP/TCP headers */
+ IPOIB_UD_HEAD_SIZE = IB_GRH_BYTES + IPOIB_ENCAP_LEN + 128,
IPOIB_UD_RX_SG = 2, /* max buffer needed for 4K mtu */
IPOIB_CM_MTU = 0x10000 - 0x10, /* padding to align header
to 16 */
diff --git a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
index 2cfa76f..9eaa58e 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_ib.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_ib.c
@@ -156,18 +156,12 @@ 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)) {
- buf_size = IPOIB_UD_HEAD_SIZE;
- tailroom = 128; /* reserve some tailroom for IP/TCP headers */
- } else {
- buf_size = IPOIB_UD_BUF_SIZE(priv->max_ib_mtu);
- tailroom = 0;
- }
+ buf_size = ipoib_ud_need_sg(priv->max_ib_mtu) ?
+ IPOIB_UD_HEAD_SIZE : IPOIB_UD_BUF_SIZE(priv->max_ib_mtu);
- skb = dev_alloc_skb(buf_size + tailroom + 4);
+ skb = dev_alloc_skb(buf_size + 4);
if (unlikely(!skb))
return NULL;
--
1.8.1.2
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