On Tue, 13 Nov 2012 16:03:00 -0800
"Paul E. McKenney" [off-list ref] wrote:

Just to make sure I am really understanding what is happening, let's
suppose we have a HZ=1000 system that has a few tasks that
occasionally run at prio 99.  These tasks would run during the clamp
interval, but would (for example) see the jiffies counter remaining
at the value at the beginning of the clamp interval until the end of
that interval, when the jiffies counter would suddenly jump by roughly
six counts, right?

Yes, if there is no interrupts disturb the clamping duration.
We do not mask interrupts which will update jiffies.

-- 
Thanks,

Jacob