Re: [RFC][PATCH 5/5] perfcounter: Add support for kernel hardware breakpoints

[Frédéric Weisbecker]

2009/7/20, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>:
> On Mon, 2009-07-20 at 13:08 -0400, Frederic Weisbecker wrote:
>> This adds the support for kernel hardware breakpoints in perfcounter.
>> It is added as a new type of software counter and can be defined by
>> using the counter number 5 and by passsing the address of the
>> breakpoint to set through the config attribute.
>
> This seems to be IP based breakpoints. Are there plans for data based
> breakpoints as well? In that case we might want to think about the
> namespace issue, we cannot both call them breakpoint/bp etc.. ;-)


Nop, by default these breakpoints trigger on READ/WRITE accesses, it's
meant for data.
The example in the changelog profiles the bkl accesses, not by tracing
lock_kernel() or so...but by tracing the kernel_flag spinlock itself.

So it's the opposite, we may start thinking about naming issues
against possible future plans
for IP breakpoint :-)

But actually for the latter case, I would suggest Kprobe...

Damn, I forgot Masami in the Cc list...
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/