This fix a performance bug introduced by commit 90b1ebe "mlx4: set
maximal number of default RSS queues", which limits the numbers of IRQs
opened by core module.
The limit should be on the number of queues in the indirection table -
rx_rings, and not on the number of IRQ's. Also, limiting on mlx4_core
initialization instead of in mlx4_en, prevented using "ethtool -L" to
utilize all the CPU's, when performance mode is prefered, since limiting
this number to 8 reduces overall packet rate by 15%-50% in multiple TCP
streams applications.
For example, after running ethtool -L <ethx> rx 16
Packet rate
Before the fix 897799
After the fix 1142070
Results were obtained using netperf:
S=200 ; ( for i in $(seq 1 $S) ; do ( \
netperf -H 11.7.13.55 -t TCP_RR -l 30 &) ; \
wait ; done | grep "1 1" | awk '{SUM+=$6} END {print SUM}' )
CC: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ido Shamay <idos@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
bb2146bc88