Re: [PATCH] eal/armv8: high-resolution cycle counter

2016-08-19 18:22, Jerin Jacob:

On Fri, Aug 19, 2016 at 02:24:58PM +0200, Jan Viktorin wrote:

quoted

On Fri, 19 Aug 2016 17:16:12 +0530
Jerin Jacob [off-list ref] wrote:


I've got a private kernel driver enabling and disabling (hopefully) properly
this for ARMv7. If we'd like to merge it, I'd like to have a single module
or at least single module with 2 implementations...

I can post it if it would be helpful.

I don't think we can use this in production as this may alter PMU state used
by 'perf' etc.I think let it be a debug interface for armv7 and armv8
and disable it by default.

Please could you document the use of PMU for debug and how it alters
usage of kernel counters?
A patch in doc/guides/prog_guide/profile_app.rst would be welcome.

Ideally, it would be a lot better to have a sysfs entry to enable PMU
counter with an upstream kernel.