[PATCH] arm: dts: exynos5: Remove multi core timer

Chirantan Ekbote chirantan at chromium.org
Thu May 15 16:03:24 PDT 2014

Hi Tomasz,

On Thu, May 15, 2014 at 3:44 PM, Doug Anderson <dianders at chromium.org> wrote:
> Tomasz,
> On Thu, May 15, 2014 at 3:13 PM, Tomasz Figa <tomasz.figa at gmail.com> wrote:
>>> NOTE: if for some reason we need to keep the MCT around, we're
>>> definitely going to need to account for the fact that tweaking it
>>> affects the arch timer.  ...and having the arch timer is really nice
>>> since:
>> [Let me reorder the points below to make it easier to comment:]
>>> * it's faster to access.
>>> * it is accessible from userspace for really fast access.
>> Do you have some data on whether it is a significant difference,
>> especially considering real use cases?
> I know that Chrome makes _a lot_ of calls to gettimeofday() for
> profiling purposes, enough that it showed up on benchmarks.  In fact,
> we made a change to the MCT to make accesses faster and there's a
> small mention of the benchmarking that was done at:
> https://chromium-review.googlesource.com/#/c/32190/
> ...that change probably should be sent upstream, actually.
> I'll let Chirantan comment on how much faster arch timers were.
> ...and I think David Riley (also CCed now) may be able to comment on
> the benefits of userspace timers.

When I profiled gettimeofday() calls, they were about 50 - 60% faster
with the arch timers compared to the mct.

- Chirantan

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