Patchwork [2/5] powerpc, perf: Enable conditional branch filter for POWER8

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Submitter Anshuman Khandual
Date May 22, 2013, 6:22 a.m.
Message ID <1369203761-12649-3-git-send-email-khandual@linux.vnet.ibm.com>
Download mbox | patch
Permalink /patch/245544/
State Not Applicable
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Comments

Anshuman Khandual - May 22, 2013, 6:22 a.m.
Enables conditional branch filter support for POWER8
utilizing MMCRA register based filter and also invalidates
a BHRB branch filter combination involving conditional
branches.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
---
 arch/powerpc/perf/power8-pmu.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
Peter Zijlstra - May 22, 2013, 7:53 a.m.
On Wed, May 22, 2013 at 11:52:38AM +0530, Anshuman Khandual wrote:
> Enables conditional branch filter support for POWER8
> utilizing MMCRA register based filter and also invalidates
> a BHRB branch filter combination involving conditional
> branches.
> 
> Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
> ---
>  arch/powerpc/perf/power8-pmu.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c
> index 8ed323d..e60b38f 100644
> --- a/arch/powerpc/perf/power8-pmu.c
> +++ b/arch/powerpc/perf/power8-pmu.c
> @@ -548,11 +548,21 @@ static u64 power8_bhrb_filter_map(u64 branch_sample_type)
>  	if (branch_sample_type & PERF_SAMPLE_BRANCH_IND_CALL)
>  		return -1;
>  
> +	/* Invalid branch filter combination - HW does not support */
> +	if ((branch_sample_type & PERF_SAMPLE_BRANCH_ANY_CALL) &&
> +			(branch_sample_type & PERF_SAMPLE_BRANCH_COND))
> +		return -1;
> +
>  	if (branch_sample_type & PERF_SAMPLE_BRANCH_ANY_CALL) {
>  		pmu_bhrb_filter |= POWER8_MMCRA_IFM1;
>  		return pmu_bhrb_filter;
>  	}
>  
> +	if (branch_sample_type & PERF_SAMPLE_BRANCH_COND) {
> +		pmu_bhrb_filter |= POWER8_MMCRA_IFM3;
> +		return pmu_bhrb_filter;
> +	}
> +
>  	/* Every thing else is unsupported */
>  	return -1;
>  }

So I suppose you've seen what x86 does in this case? ;-) I'm not saying
you _have_ to do the software filter, but I would like the changelog to at
least mention the issue.

In fact, I suppose that should have been in the original patches :/ as
this patch series only adds the conditional branch support.
Michael Neuling - May 22, 2013, 10:20 a.m.
Peter Zijlstra <peterz@infradead.org> wrote:

> On Wed, May 22, 2013 at 11:52:38AM +0530, Anshuman Khandual wrote:
> > Enables conditional branch filter support for POWER8
> > utilizing MMCRA register based filter and also invalidates
> > a BHRB branch filter combination involving conditional
> > branches.
> > 
> > Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
> > ---
> >  arch/powerpc/perf/power8-pmu.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c
> > index 8ed323d..e60b38f 100644
> > --- a/arch/powerpc/perf/power8-pmu.c
> > +++ b/arch/powerpc/perf/power8-pmu.c
> > @@ -548,11 +548,21 @@ static u64 power8_bhrb_filter_map(u64 branch_sample_type)
> >  	if (branch_sample_type & PERF_SAMPLE_BRANCH_IND_CALL)
> >  		return -1;
> >  
> > +	/* Invalid branch filter combination - HW does not support */
> > +	if ((branch_sample_type & PERF_SAMPLE_BRANCH_ANY_CALL) &&
> > +			(branch_sample_type & PERF_SAMPLE_BRANCH_COND))
> > +		return -1;
> > +
> >  	if (branch_sample_type & PERF_SAMPLE_BRANCH_ANY_CALL) {
> >  		pmu_bhrb_filter |= POWER8_MMCRA_IFM1;
> >  		return pmu_bhrb_filter;
> >  	}
> >  
> > +	if (branch_sample_type & PERF_SAMPLE_BRANCH_COND) {
> > +		pmu_bhrb_filter |= POWER8_MMCRA_IFM3;
> > +		return pmu_bhrb_filter;
> > +	}
> > +
> >  	/* Every thing else is unsupported */
> >  	return -1;
> >  }
> 
> So I suppose you've seen what x86 does in this case? ;-) I'm not saying
> you _have_ to do the software filter, but I would like the changelog to at
> least mention the issue.
> 
> In fact, I suppose that should have been in the original patches :/ as
> this patch series only adds the conditional branch support. 

Anshuman,

Now we have the branch reading and parsing code (for the "to" case), we
should use that to do what Peter is suggesting.  

Mikey

Patch

diff --git a/arch/powerpc/perf/power8-pmu.c b/arch/powerpc/perf/power8-pmu.c
index 8ed323d..e60b38f 100644
--- a/arch/powerpc/perf/power8-pmu.c
+++ b/arch/powerpc/perf/power8-pmu.c
@@ -548,11 +548,21 @@  static u64 power8_bhrb_filter_map(u64 branch_sample_type)
 	if (branch_sample_type & PERF_SAMPLE_BRANCH_IND_CALL)
 		return -1;
 
+	/* Invalid branch filter combination - HW does not support */
+	if ((branch_sample_type & PERF_SAMPLE_BRANCH_ANY_CALL) &&
+			(branch_sample_type & PERF_SAMPLE_BRANCH_COND))
+		return -1;
+
 	if (branch_sample_type & PERF_SAMPLE_BRANCH_ANY_CALL) {
 		pmu_bhrb_filter |= POWER8_MMCRA_IFM1;
 		return pmu_bhrb_filter;
 	}
 
+	if (branch_sample_type & PERF_SAMPLE_BRANCH_COND) {
+		pmu_bhrb_filter |= POWER8_MMCRA_IFM3;
+		return pmu_bhrb_filter;
+	}
+
 	/* Every thing else is unsupported */
 	return -1;
 }