On Wed, 2012-01-25 at 09:55 +0100, Uwe Kleine-König wrote:

Hello,

On Tue, Jan 24, 2012 at 06:39:34PM -0800, Venkat Subbiah wrote:

quoted

In the process of debugging a napi ethernet driver performance
issue, what I am noticing is

1. While the driver is in the middle of a napi packet processing
loop, there is a task switch from
sirq-net-rx to idle even though there is pending napi processing to be done.

I didn't check your logs below, but maybe this is related to the default
settings in /proc/sys/kernel/sched_rt_period_us and
/proc/sys/kernel/sched_rt_runtime_us? That is 0.05s per second is
reserved for non-RT tasks tasks such that a run-away realtime process
will not lock up the machine.

To verify that, try

	echo -1 > /proc/sys/kernel/sched_rt_runtime_us

Hm, makes sense if this is a UP box.  SMP would just go borrow a cup of
runtime from a neighbor.

	-Mike

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