Re: [PATCH 1/3] Updated dynamic tick patches - Fix lost tick calculation in timer_pm.c

[john stultz <johnstul@us.ibm.com>]

On Sat, 2005-09-03 at 00:05 -0400, Lee Revell wrote:
> On Wed, 2005-08-31 at 22:42 +0530, Srivatsa Vaddagiri wrote:
> > With this patch, time had kept up really well on one particular
> > machine (Intel 4way Pentium 3 box) overnight, while
> > on another newer machine (Intel 4way Xeon with HT) it didnt do so
> > well (time sped up after 3 or 4 hours). Hence I consider this
> > particular patch will need more review/work.
> > 
> 
> Are lost ticks really that common?  If so, any idea what's disabling
> interrupts for so long (or if it's a hardware issue)?  And if not, it
> seems like you'd need an artificial way to simulate lost ticks in order
> to test this stuff.

Pavel came up with a pretty good test for this awhile back.

http://marc.theaimsgroup.com/?l=linux-kernel&m=110519095425851&w=2

Adding:
	unsigned long mask = 0x1;
	sched_setaffinity(0, sizeof(mask), &mask);

to the top helps it work on SMP systems.

thanks
-john

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