* Guidelines to make RT patch for driver
@ 2012-03-30 16:22 Mikhail Lodigin
2012-04-13 8:21 ` Thomas Gleixner
0 siblings, 1 reply; 2+ messages in thread
From: Mikhail Lodigin @ 2012-03-30 16:22 UTC (permalink / raw)
To: linux-rt-users
Hello,
on my AT91SAM9263 based board RT patched kernel works great! Thanks to
all involved. But when ethernet is in use - latency, measured by
cyclictest, reach 7000000 and beyond.
The ethernet driver for this processor is macb.c. (in 3.2 it is in
drivers/net/ethernet/cadence, in 3.0 it is in drivers/net/).
I'm ready to find out how to RT-patch it and of course share the
resulted patch, but I need some starting point for patching drivers
besides general RT-stuff. I've noticed that some network drivers
patched in one way and others a in another. Maybe some discussion
existed which I didn't found. So any help would be greatly appreciated.
Thanks in advance,
Mikhail
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Guidelines to make RT patch for driver
2012-03-30 16:22 Guidelines to make RT patch for driver Mikhail Lodigin
@ 2012-04-13 8:21 ` Thomas Gleixner
0 siblings, 0 replies; 2+ messages in thread
From: Thomas Gleixner @ 2012-04-13 8:21 UTC (permalink / raw)
To: Mikhail Lodigin; +Cc: linux-rt-users
On Fri, 30 Mar 2012, Mikhail Lodigin wrote:
> Hello,
> on my AT91SAM9263 based board RT patched kernel works great! Thanks to all
> involved. But when ethernet is in use - latency, measured by cyclictest, reach
> 7000000 and beyond.
> The ethernet driver for this processor is macb.c. (in 3.2 it is in
> drivers/net/ethernet/cadence, in 3.0 it is in drivers/net/).
> I'm ready to find out how to RT-patch it and of course share the resulted
> patch, but I need some starting point for patching drivers besides general
> RT-stuff. I've noticed that some network drivers patched in one way and
> others a in another. Maybe some discussion existed which I didn't found. So
> any help would be greatly appreciated.
There is no general recipe. The best way to do it is to use the
tracer. cyclictest has a commandline option for stopping the trace
when the latency exceeds a given treshold.
cyclictest -p80 -n -f -b 1000
will start the function tracer and stop it once the latency exceeds
1000us.
Thanks,
tglx
^ permalink raw reply [flat|nested] 2+ messages in thread
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2012-03-30 16:22 Guidelines to make RT patch for driver Mikhail Lodigin
2012-04-13 8:21 ` Thomas Gleixner
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