On 27.09.10 18:26:27, Matt Fleming wrote:

On Tue, Sep 28, 2010 at 12:07:03AM +0200, Robert Richter wrote:

quoted

On 27.09.10 16:01:38, Matt Fleming wrote:

quoted

On Thu, Sep 16, 2010 at 04:32:54PM +0200, Robert Richter wrote:

quoted

quoted

diff --git a/arch/sh/kernel/perf_event.c b/arch/sh/kernel/perf_event.c
index 2cb9ad5..3c3fc9a 100644
--- a/arch/sh/kernel/perf_event.c
+++ b/arch/sh/kernel/perf_event.c

@@ -59,6 +59,14 @@ static inline int sh_pmu_initialized(void)
 	return !!sh_pmu;
 }
 
+const char *sh_pmu_name(void)
+{
+	if (!sh_pmu)
+		return NULL;
+
+	return sh_pmu->name;
+}

Couldn't we make this a generic function like perf_num_counters()?

Well, ARM doesn't have names as strings for its pmus currently. What's
more, ARM wouldn't use it; SH would be the only user of this function. I
don't think this one makes sense to be a generic function.

I didn't catch this with my first review, the function will need an
EXPORT_SYMBOL_GPL() to allow building modules. This will mean an
interface extension what should be non-arch. So, for architectures we
need the pmu name like SH we just implement the generic function. For
ARM we don't need to provide this function.

Yeah my bad, I just hit this EXPORT_SYMBOL_GPL issue when compiling
oprofile as a module.

quoted

Most of the interface is defined in linux/perf_event.h. We shouldn't
move this to asm/perf_event.h, so this is one more argument for the
non-arch implementation.

I'm not advocating moving this function to asm/perf_event.h.

quoted

As the implementation of the function would be optional, why should we
make it architectural?

I don't see why we should pollute the perf namespace with a function
that is only being used inside the SH oprofile code? There would be
exactly one use of this function and I doubt the perf guys will want
this function exposed. In it's current state, it really is no use to any
architecture other than SH.

We can always add a generic perf_pmu_name() function later if needed,
but it's definitely not needed at the moment.

Ok, so then let's implement sh_pmu_name() in
arch/sh/oprofile/common.c, we import asm/perf_event.h to get access to
struct sh_pmu. This could be implemented as a static function then and
we also get rid of this interface thing.

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center