Re: [PATCH v2 4/4] perf/x86/intel/pt: Opportunistically use single range output mode

[Alexander Shishkin]

Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:

> On Tue, Oct 22, 2019 at 12:58:12PM +0300, Alexander Shishkin wrote:
>> Most of PT implementations support Single Range Output mode, which is
>> an alternative to ToPA that can be used for a single contiguous buffer
>> and if we don't require an interrupt, that is, in AUX snapshot mode.
>> 
>> Now that perf core will use high order allocations for the AUX buffer,
>> in many cases the first condition will also be satisfied.
>> 
>> The two most obvious benefits of the Single Range Output mode over the
>> ToPA are:
>>  * not having to allocate the ToPA table(s),
>>  * not using the ToPA walk hardware.
>> 
>> Make use of this functionality where available and appropriate.
>
> This seems independent of the snapshot stuff, right?

Yes, it depends on the previous PT driver patch for context,
though. I'll drop it from the set.

Regards,
--
Alex