Re: [RFC] clocksouce implementation for powerpc

On Wed, Jun 20, 2007 at 07:57:19AM -0700, Daniel Walker wrote:

Hi Daniel.

As I said in our private thread, I do think you should be using
update_vsyscall() .. update_vsyscall() is just called when the time is
set, usually that happens in the timer interrupt and sometimes that
happens in settimeofday() ..

Well I've taken another look at the code and I think I can probably
restructure my code to use update_vsyscall().  I thought I needed a
hook that was called /only/ from settimeofday() (which as you say
doesn't match update_vsyscall()'s usage).

I'll try again and see what problems I hit.
 

At least some of your code is duplications over what is already being
worked on inside the powerpc community.. For instance, I know there is
already a timebase clocksource,

http://people.redhat.com/~mingo/realtime-preempt/patch-2.6.21.5-rt17

Thanks. The one in -rt doesn't seem to support the VDSO.  however I see
that there is duplication of effort there.
 

Hmm .. This doesn't look like it's taking into account that the time has
changed .. Your time has effectively incremented by one jiffie .. The
vdso_data doesn't appear to be updated ..

Unless I miss your meaning, the vdso is updated in
timer_recalc_offset()/update_gtod() when needed.

Yours Tony

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