TSO4 network problems and scheduler selection

[Artem Kuchin]

Hi!

A couple of weeks ago i have written about TSO4 problems on em
network interface. The problem was that when TSO4 is enable
em stream send perfomace drop to about ZERO. (i cannot download
any file from ftp, i canont even get midnight commander to draw
a full screen in ssh client). Noone has found any solution and
it was decided that it was a bug in em driver.

Today i have played with SCHED_ULE scheduler on this box 
(it is 7-CURRENT, Pentium D). Adn accidentaly found out that
when SCHED_ULE is selected TSO4 does not cause any problems.

My interface:

em0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=18b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWCSUM,TSO4>


This is totally weird, but i'm letting everybody know it if
someone step into this problem. Viva SCHED_ULE!

--
Regards,
Artem