e1000: fix flow control thresholds

when testing the jumbo frames with pages patch, the stats would
show rx_missed errors (dropped packets) even when connected to a
link partner with flow control enabled.

this indicates that for this MTU (9000) the flow control
thresholds are not adjusting correctly.

In fact, before this change, the FCRTH (xoff threshold) is 36864
when the fifo size is only 40000, with 9000 byte MTU.

fix it so that we at least have room for one frame after we send
the xoff.

Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jesse Brandeburg 2009-07-06 10:45:01 +00:00 • committed by David S. Miller
commit b7cb8c2c82
3 changed files with 33 additions and 30 deletions