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Date: Tue, 31 May 2011 23:26:32 +0530
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From: "Jayachandran C." <c.jayachandran@gmail.com>
To: Adrian Chadd <adrian@freebsd.org>
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Cc: freebsd-mips@freebsd.org
Subject: Re: hwpmc and mips?
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On Tue, May 31, 2011 at 3:38 PM, Adrian Chadd <adrian@freebsd.org> wrote:
> On 31 May 2011 18:00, Adrian Chadd <adrian@freebsd.org> wrote:
>
>> I'm likely going to look at this sometime after July (and I'm sure
>> it's just a case of hooking into the right IRQ handler) but if someone
>> beat me to it *hint*, I'd very much appreciate it.
>
> To prove I'm not completely slack, I went spelunking through the
> source to see how hwpmc hooks into things.
>
> There's no HWPMC_HOOKS used anywhere in sys/mips/* or sys/mips/*/*,
> save config files.
>
> I thus have a feeling the hwpmc glue for sampling mode just isn't
> there for any MIPS core at the present time.
>
> Would someone more versed in the ways of MIPS stack frame magic and
> trap handling care to take a stab at it?

We have some work in progress on hwpmc on XLR, there is a hang on SMP
which we need to fix before merging it. The counters are very
different from the mips24k, and unfortunately the counters generated
the same interrupt as the count/compare timer.

On mips, getting the stack trace is going to be difficult - I'm not
sure if this can be done efficiently in the pmc interrupt handler at
all.

JC.