[RFC] [PATCH] Trace TLBIE's

[Michael Ellerman]

Alistair Popple <alistair at popple.id.au> writes:

> On Wed, 23 Nov 2016 10:40:36 PM Balbir Singh wrote:
>>
>> > But overall I guess it's OK. We'd want to do a quick benchmark to make
>> > sure it's not adding any overhead.
>>
>> OK.. I'll try and find a benchmark and run it with traces disabled.
>
> For what's it's worth I didn't notice any slow down running a NAMD
> test with tracing disabled and ~400000 tlbie's in 34s. Turning tracing
> on could have slowed things down ever so slightly, but I didn't notice
> as it may have just been in the noise of the benchmark I was running
> (I wasn't specifically looking at timing, hence the vagueness of the
> remarks).
>
> Otherwise the patch worked and would be useful - I have already had to
> setup tlbie counting/tracing several times in the last 12 months.
>
> Tested-by: Alistair Popple <alistair at popple.id.au>

OK thanks.

To get it merged I'd like:
 - always called after the barriers.
 - no calls in loops, instead add a "count" field to the trace point and
   when we call it multiple times in a loop we pass the count.

So you'd see entries something like:

<...>-5141  [062]  1354.486693: tlbie: lpid=0, local=1, rb=0x7b5d0ff874f11f1, rs=0, ric=0, prs=0, r=0, count=128

cheers