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

[Thomas Monjalon]

2016-08-19 18:22, Jerin Jacob:
> On Fri, Aug 19, 2016 at 02:24:58PM +0200, Jan Viktorin wrote:
> > On Fri, 19 Aug 2016 17:16:12 +0530
> > Jerin Jacob <jerin.jacob at caviumnetworks.com> 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.