[PATCH] powerpc, perf: Configure BHRB filter before enabling PMU interrupts

Michael Ellerman michael at ellerman.id.au
Tue Oct 8 15:21:37 EST 2013

On Mon, Oct 07, 2013 at 10:00:26AM +0530, Anshuman Khandual wrote:
> Right now the `config_bhrb` PMU specific call happens after write_mmcr0
> which actually enables the PMU for event counting and interrupt. So
> there is a small window of time where the PMU and BHRB runs without the
> required HW branch filter (if any) enabled in BHRB. This can cause some
> of the branch samples to be collected through BHRB without any filter
> being applied and hence affecting the correctness of the results. This
> patch moves the BHRB config function call before enabling the interrupts.

Patch looks good.

But it reminds me I have an item in my TODO list:
 - "Why can't config_bhrb() be done in compute_mmcr()" ?


More information about the Linuxppc-dev mailing list