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    SubjectRe: [RFC][PATCH] Convert alpha to use clocksource
    On Thu, Mar 18, 2010 at 10:55:23AM -0700, john stultz wrote:
    > On Thu, 2010-03-18 at 07:32 -0700, Richard Henderson wrote:
    > > On 03/17/2010 07:01 PM, John Stultz wrote:
    > > > Alpha has a tsc like rpcc counter that it uses to manage time.
    > > > This can be converted to an actual clocksource instead of utilizing
    > > > the arch_gettimeoffset method that is really only there for legacy
    > > > systems with no continuous counter.
    > >
    > > With 8 seconds or less between roll-overs, do you actually consider
    > > this a continuous counter? I don't. I suggest this be left alone.
    > The timekeeping code handles this (although the shift value I picked may
    > need some adjustment - what is the expected counter freq range on
    > alpha?). The ACPI PM counter which is very common on x86 is only 24 bits
    > and rolls over in ~5 seconds. It works fine.

    Yeah, that looks cool. I'm typing this on the 800MHz UP1500 running
    2.6.34-rc1 plus your patch, and the timekeeping works fine so far.

    Though, even after a glance over the clocksource code, I've not
    gotten yet to how one could estimate the "shift" value...
    Any hints?

    And if I recall correctly, production alphas have been clocked
    in the range of 60-1250 MHz.


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