Re: [PATCH] Remove Powerpc OProfile events the kernel will reject

On 11/17/2015 12:02 PM, Carl E. Love wrote:
> On Mon, 2015-11-16 at 17:38 -0500, William Cohen wrote:
>>
>> Hi Carl,
>>
>> So if I am reading the comment around line 326 the code is allowed to
>> have the msb of cache_sel be 1 so long as the lower 3 bits are zero.
>> Thus, 8 and 0 are allowed in for the cache_sel nibble and the
>> currently proposed patch does exclude the problem pmu events.
>>
> 
> That is the way I read it.  When I tested the events with a cache field
> of 8 were not rejected.  Unfortunately, I can't verify the accuracy of
> the counts.  
> 
> Basically I took the entire events file (events/ppc64/power8/events),
> ran some scripts on it to extract the event names for all of the events
> that are not commented out.  The list of names were then put into a
> script file to run each of the events on a simple workload to verify if
> the events were accepted or rejected.  I claim that after the patch is
> applied, all of the remaining events will be accepted as a valid event
> by the kernel.  
> 
> I don't have the documentation on the HW bug to validate that the
> comment in the code is accurate and the results of events with a cache
> field of 8 really do work.  
> 
> 
>> The libpfm4/lib/events/power8.h has:
>>
>> * Documentation on the PMU events will be published at:
>> *  http://www.power.org/documentation
>>
> Yea, I tried the web site and the site doesn't seem to exist.  I sent
> off an email to the IBM HW team to find out what is going on.  I will
> let you know when I can track down a working link.  Thanks for noticing
> the link is broken.
> 
>               Carl Love

Hi Carl,

The patch for eliminating the problem power 8 pmu events looks reasonable, so I committed it to the oprofile repository.  Thanks for the fix.

When a proper pointer to the power8 pmu counter documentation becomes available there should be a patch to utils/ophelp.c.  It currently has the following in there, but search for "Power ISA 2.07" doesn't turn up anything on the www.power.org website.

	case CPU_PPC64_ARCH_V1:
	case CPU_PPC64_POWER8:
		event_doc =
			"This processor type is fully supported with operf.\n"
			"See Power ISA 2.07 at https://www.power.org/\n\n";
		break;

-Will

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