polling decreases throughput ~50%

Victor Semionov victor at vmpbg.com
Wed Aug 3 09:23:12 GMT 2005

> >> Why is that? I thought polling should decrease CPU usage by avoiding too
> >> many context switches when a hw irq is generated frequently, but it
> >> shouldn't make the transfer slower if there are no other jobs running.
> You have to poll often enough to keep the pipe full, otherwise your max
> throughput can be limited.  Also, rl hardware isn't the greatest and
> probably requires a lot more CPU than a device with working buffer/DMA
> design.

HZ is 1000, which I guess should be more than enough with 

Indeed, it was hardware's fault - my other NIC is a fxp and I got much better 
results with it - less CPU, while throughput stayed the same as without 

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