Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [RFC] [PATCH] allow low HZ values? | Date | Tue, 12 Oct 2010 16:31:20 +0200 |
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Thomas Gleixner <tglx@linutronix.de> writes:
> On Mon, 11 Oct 2010, Tim Pepper wrote: > >> I'm not necessarily wanting to open up the age old question of "what is >> a good HZ", but we were doing some testing on timer tick overheads for >> HPC applications and this came up... > > Yeah. This comes always up when the timer tick overhead on HPC is > tested. And this patch is again the fundamentally wrong answer.
That's a unfair description of the proposal.
> We have told HPC folks for years that we need a kind of "NOHZ" mode > for HPC where we can transparently switch off the tick when only one > user space bound thread is active and switch back to normal once this > thing terminates or goes into the kernel via a syscall. Sigh, nothing > happened ever except for repeating the same crap patches over and > over.
Jan Blunck posted a patch for this exactly few months ago. Unfortunately it didn't get the accounting right, but other than that it seemed like a reasonable starting point.
-Andi -- ak@linux.intel.com -- Speaking for myself only.
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