Re: Ethernet bridge performance

Felix Radensky writes:

 > Is slab good enough in 2.4 ? I was thinking that one of the goals
 > of skb-recycle patch was to avoid skb allocations and deallocations
 > which consume quite a lot of CPU time (as profile shows). Are you
 > saying that your patch is not hepling to reduce CPU load ?
 
 Try to understand why/where packets get dropped in your setup to start with.
 Bridging shouldn't be different from routing which I experiments with.

 Check /proc/interrupts, /proc/net/softnet_stat and check for drops at 
 qdisc ( "tc -s qdisc" you might have to readd the qdisc just get the stats)

 Possible your TX-side cannot keep up with RX. Often the TX ring is not
 cleard aggressivly enough at high rates due intr. mitigation etc or possibly
 HW_FLOWCTRL from sink device. Disable it in your for testing.

 When you cure the cause in-kernel-drop you should have packets drops
 on the DMA-ring (in the driver) with NAPI drivers and no unnecssary
 skb allocation/CPU use or DMA's.

 > echo 1 > /proc/irq/48/smp_affinity
 > to avoid this kind of problem, or something else is required ?

 If you have both both incoming and outgoing on same CPU there will
 be no cache bouncing of course and a UP kernel would be faster if this
 all your job.

 
 Cheers.
						--ro