Re: [PATCH RFC v3 00/12] perf pmu-events: Support event aliasing for system PMUs

[John Garry]

> I have an aside question, do you have any idea? Thanks a lot!
>
> For DDR PMU, I want to add bandwidth usage metric, but it depends on DDR controller clock frequency.
> For example, we have i.MX8MM LPDDR4 board which DDR controller clock is 800MHZ, and i.MX8MM DDR4 board which DDR controller is 600MHZ, but the SoC is the same.
>
> So they can share all JSON metrics with identifier "i.mx8mm", except bandwidth metric. 

what is the bandwidth metric? how is it supposed to be calculated?

If I add separate JOSN metrics files for identifier "i.mx8mm-lpddr4" and 
identifier "i.mx8mm-ddr4", then it's going to be very redundant, since 
most metrics are same just the identifier is different.
> Do you know how perf tool handle such case?

jirka is supporting user-defined metric here:
https://lore.kernel.org/lkml/20200511205307.3107775-1-jolsa@xxxxxxxxxx/

So maybe you can use that somehow with separate scripts.

Thanks,
John