RE: [Intel-wired-lan] [PATCHv2 net-next] net: igb: Only dma sync frame length

From: Intel-wired-lan [mailto:intel-wired-lan-bounces@lists.osuosl.org] On
Behalf Of Andrew Lunn
Sent: Friday, June 3, 2016 2:03 PM
To: Kirsher, Jeffrey T <redacted>; David Miller
[off-list ref]
Cc: netdev <redacted>; intel-wired-lan@lists.osuosl.org;
Andrew Lunn [off-list ref]
Subject: [Intel-wired-lan] [PATCHv2 net-next] net: igb: Only dma sync frame
length

On some platforms, syncing a buffer for DMA is expensive. Rather than
sync the whole 2K receive buffer, only synchronise the length of the
frame, which will typically be the MTU, or a much smaller TCP ACK.

For an IMX6Q, this gives around 6% increased TCP receive performance,
which is cache operations bound and reduces CPU load for TCP transmit.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
v2:
Christmas tree the local variables
Pass size into igb_add_rx_frag() rather than repeating the endiness swap.
---
 drivers/net/ethernet/intel/igb/igb_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

Tested-by: Aaron Brown <redacted>