linux-kernel - RE: bug seen with dynticks from CONFIG_HARDIRQS_SW

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Date:	Thu, 17 May 2007 17:24:55 -0500
From:	"Woodruff, Richard" <r-woodruff2@...com>
To:	"Thomas Gleixner" <tglx@...utronix.de>
Cc:	<linux-kernel@...r.kernel.org>, "Ingo Molnar" <mingo@...e.hu>
Subject: RE: bug seen with dynticks from CONFIG_HARDIRQS_SW_RESEND

> This is the original ARM dyntick stuff, right ?

Yes this is a version is not using clocksource.

> The dyntick support on your architecture is broken. Why does it fiddle
> with the timer, when the system is not idle ?

I can't yet run the test sequence on the latest kernel so I'll have to
wait to experiment.  A brief look at the new code seems to show a
similar path but I need to actually run though it to understand better.

On the irq_resend() path handle_dynamic_tick() is still called as
before.  The difference now is the handler looks like it will jump into
some generic event code in tick-common.c.  This still calls
ticker_periodic() which calls profile_tick() in and out of one-shot
mode.

It might be the path still exists or I've just not spent enough time
understanding the real flow.

Thanks for the insight and the nice code.

> This stuff should go away ASAP. A lot of ARMs are already converted to
> clock events are using the generic NOHZ implementation, which does not
> have those problems at all.

Ok. Thanks. I look forward to using that when I can.

Regards,
Richard W. 
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