Re: HW breakpoints perf_events request

Joshua Pincus
2010-01-14T02:27:22Z

Hi,

On Wed, Jan 13, 2010 at 6:15 PM, Andi Kleen <andi@firstfloor.org> wrote:
> Joshua Pincus <joshua.pincus@gmail.com> writes:
>
>> I have a request for an additional feature to be included
>> in the recent hardware breakpoints work soon to be delivered
>> in kernel 2.6.33.
>
> Sounds to me like the existing ptrace based interface
> can practically all you want
>
> (except that the "parent signal" would be wait and for
> fork/exec you have to explicitely attach)

We would like to avoid using ptrace at all costs.
It requires us to have a parent thread running
which monitors all the others. It's not clear that
the wait() call by the parent doesn't mask a barrage
of signals from various threads and the performance
penalty is huge in multi-threaded apps.

If we could get this functionality working w/o ptrace,
we'd be very, very happy and grateful.

>
> -Andi
>

Thanks,
JP
--
On Wed, Jan 13, 2010 at 6:15 PM, Andi Kleen <andi@firstfloor.org> wrote:
> Joshua Pincus <joshua.pincus@gmail.com> writes:
>
>> I have a request for an additional feature to be included
>> in the recent hardware breakpoints work soon to be delivered
>> in kernel 2.6.33.
>
> Sounds to me like the existing ptrace based interface
> can practically all you want
>
> (except that the "parent signal" would be wait and for
> fork/exec you have to explicitely attach)
>
> -Andi
>
> --
> ak@linux.intel.com -- Speaking for myself only.
>