Re: possible time_interpolator bug?

From: David Mosberger <davidm_at_napali.hpl.hp.com>
Date: 2004-02-18 17:58:06
>>>>> On Tue, 17 Feb 2004 22:42:54 -0800, john stultz <johnstul@us.ibm.com> said:

  John> So each second, we call "_update(NSEC_PER_SEC)", however for
  John> each tick we call update_wall_time_one_tick() which calls
  John> "_update(delta_nsec)".

  John> Thus in a period of one second, we call _update() HZ times w/
  John> ~NSEC_PER_SEC/HZ as an argument, then at the second overflow
  John> we call it again w/ NSEC_PER_SEC.

  John> It seems that calling _update() on the second overflow is
  John> unnecessary.

Not just unnecessary, but wrong!

  John> It would be noted that time inconsistencies are not seen using
  John> the ITC interpolator, however the ITC interpolator has an
  John> empty _update function.

Yes.

  John> Am I just missing something here?

I don't think so.  Good bug hunting.  Some time ago SGI reported some
jumpiness but I never got a definite answer whether the problem had
been solved.

You may want to run this by someone who actually understands the code
in timer.c but I'm pretty sure you're right.

Thanks,

	--david
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Received on Wed Feb 18 02:03:27 2004

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