Re: large intermittent latency spike 2.6.28 (and 2.6.27.10), bisect commit ca7e716c7833aeaeb8fedd6d004c5f5d5e14d325 -> Revert "sched_clock: prevent scd->clock from moving backwards"

[Jayson King <dev@jaysonking.com>]

Arjan van de Ven wrote:
 > Jayson King <dev@jaysonking.com> wrote:
 >> Please disregard this. ...
 >
 > can you run latencytop to see if it can pinpoint a cause of latency?

Like I said in my other reply I was running the wrong kernel when I 
wrote that (oops)... So now I am still sure it is ca7e716.

Ingo's patch makes the same change that reverting ca7e716 does here:

-	max_clock = scd->tick_gtod + TICK_NSEC;
+	max_clock = wrap_max(scd->clock, scd->tick_gtod + TICK_NSEC);


And with that change (I'm using Ingo's patch now) I can't trigger the 
hang anymore. And before, I could reliably trigger it in a short time.

Jayson