serious networking (em) performance (ggate and NFS) problem

[Shunsuke SHINOMIYA]

 Jeremie, thank you for your comment.

 I did simple benchmark at some settings.

 I used two boxes which are single Xeon 2.4GHz with on-boarded em.
 I measured a TCP throughput by iperf.

 These results show that the throughput of TCP increased if Interrupt
Moderation is turned OFF. At least, adjusting these parameters affected
TCP performance. Other appropriate combination of parameter may exist.


 The settings are some combinations of
hw.em0.rx_int_delay
hw.em0.tx_int_delay
hw.em0.rx_abs_int_delay
hw.em0.tx_abs_int_delay
hw.em0.int_throttle_ceil.

In this mail, A setting, 
hw.em0.rx_int_delay: 0
hw.em0.tx_int_delay: 66
hw.em0.rx_abs_int_delay: 66
hw.em0.tx_abs_int_delay: 66
hw.em0.int_throttle_ceil: 8000
is abbreviated to (0, 66, 66, 66, 8000).

TCP window size was not adjusted by iperf's options. It mean that iperf
is used by default setting.

sender : default(0, 66, 66, 66, 8000), receiver : default(0, 66, 66, 66,
8000)
1st trial 852Mbps
2nd trial 861Mbps
3rd trial 822Mbps
4th trial 791Mbps
5th trial 826Mbps
average 830.4Mbps, std. dev. 27.6Mbps

sender : (0, 0, 0, 0, 8000), receiver : (0, 0, 0, 0, 8000)
1st trial 787Mbps
2nd trial 793Mbps
3rd trial 843Mbps
4th trial 771Mbps
5th trial 848Mbps
average 808.4Mbps, std. dev. 34.9Mbps

sender : off(0, 0, 0, 0, 0), receiver : off(0, 0, 0, 0, 0)
1st trial 902Mbps
2nd trial 901Mbps
3rd trial 899Mbps
4th trial 894Mbps
5th trial 900Mbps
average 899.2Mbps, std. dev. 3.1Mbps

-- 
Shunsuke SHINOMIYA <shino at fornext.org>