RE: kernel performance update - 2.6.14-rc3

[Chen, Kenneth W]

Jon Burgess wrote on Friday, October 07, 2005 5:50 PM
> "Chen, Kenneth W" <kenneth.w.chen@xxxxxxxxx> writes:
> > Even though
> > softirq is invoked at the end of dev_queue_xmit() via local_bh_enable(),
> > not all execution of softirq will result a __wake_up().  With higher
> > HZ rate, timer interrupt is more frequent and thus more softirq
> > invocation and leads to more __wake_up(), which then takes us to higher
> > throughput because cpu spend less time in idle.
> 
> Since the loopback xmit->rx path probably isn't being called in 
> interrupt context might something like the patch below be needed?
> 
> Please forgive me if this is wrong, i've not even tried compiling
> this change let alone tested it.

I don't think this patch has any effect.  dev_queue_xmit turns off
local_bh when calling loopback_xmit, so calls to do_softirq from
netif_rx_ni Will be a noop since do_softirq immediately return upon
seeing in_interrupt().

- Ken

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