Tomasz, On Thu, May 15, 2014 at 3:13 PM, Tomasz Figa <tomasz.figa@xxxxxxxxx> 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. >> * it implements the bits needed for udelay() to use it. > > Hmm, do you know what bits are those? On Exynos4 MCT is the only option > and it would be nice to let udelay() use it. Look for register_current_timer_delay(). It seems like we could do this for MCT, but I've never done the investigation because we were always planning to move to arch timers. ;) -Doug -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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