DragonFly commits List (threaded) for 2012-12
git: igb: Improve tiny packets reception performance on low frequency CPU
Author: Sepherosa Ziehau <firstname.lastname@example.org>
Date: Sun Dec 9 14:36:20 2012 +0800
igb: Improve tiny packets reception performance on low frequency CPU
Update RDT register a little bit often, so the RX descriptors are made
to the NIC chip on a more regularly base:
The RDT register is updated after certain amount of RX descriptors are
added to the hardware RX ring. The default value of the amount of RX
descriptors are 32. This value could be further tuned by per-device
sysctl node hw.igbX.rxY_wreg.
The default value improves tiny packets reception performance w/ 82576
on AMD970@800Mhz under interrupt mode for single stream (1.28Mpps ->
1.48Mpps) and it does not increase CPU usage on AMD970@3500Mhz (CPU
usage stays @36%).
This commit does _not_ seem to affect the tiny packet reception
performance when the workload are evenly distributed to all CPUs.
Summary of changes:
sys/dev/netif/igb/if_igb.c | 37 ++++++++++++++++++++++++++++++++-----
sys/dev/netif/igb/if_igb.h | 1 +
2 files changed, 33 insertions(+), 5 deletions(-)
DragonFly BSD source repository