[gprofng] Adding a new CPU architecture

[gprofng] Adding a new CPU architecture

[Thomas Gruber]

Hi,

I tried to add Fujitsu A64FX hardware performance event support to 
gprofng but didn't find a contributing guide. The comments in the code 
and the code structure itself didn't help much in my understanding.

Just adding the event list is probably not enough since the A64FX is not 
detected properly yet by gprofng, so extending the CPU detection is also 
required.

Are there some hints how to add a new architecture to gprofng?

Best,
Thomas

-- 
Thomas Gruber
Software & Tools
Erlangen National High Performance Computing Center (NHR@FAU)
Friedrich-Alexander University Erlangen-Nürnberg
Martensstraße 1, 91058 Erlangen, Germany
mailto:Thomas.Gruber@fau.de
https://hpc.fau.de/

Re: [gprofng] Adding a new CPU architecture

[Vladimir Mezentsev]

Hi Thomas,

On 3/22/22 04:52, Thomas Gruber wrote:
> Hi,
>
> I tried to add Fujitsu A64FX hardware performance event support to 
> gprofng 

Super.
Welcome to the gprofng team.


> but didn't find a contributing guide. The comments in the code and the 
> code structure itself didn't help much in my understanding.
>
> Just adding the event list is probably not enough since the A64FX is 
> not detected properly yet by gprofng, so extending the CPU detection 
> is also required.
>
> Are there some hints how to add a new architecture to gprofng?

No.

Historically, HWC profiling has been based on different APIs ( libcpc, 
libperfctr, ... ).
Currently only the perf_even API is used ( See 
https://man7.org/linux/man-pages/man2/perf_event_open.2.html )

To add HWC support for a new architecture, you need to complete the 
following steps:
   - Add a new cpu type. See gprofng/common/cpuid.c and 
gprofng/common/hwc_cpus.h
   - Add tables in gprofng/common/hwctable.c. See lines around 2374 for 
an example.
   - If necessary,  change init_perf_event() in gprofng/common/hwcdrv.c 
line ~678.


Thank you,
-Vladimir


>
> Best,
> Thomas
>