Dynamic Ticks/HZ

Joe Holden lists at rewt.org.uk
Mon Nov 5 06:40:55 UTC 2012

Davide Italiano wrote:
> On Mon, Nov 5, 2012 at 7:12 AM, Joe Holden <lists at rewt.org.uk> wrote:
>> Hi guys,
>> Has some default changed between 9.1-RC2 and HEAD?
>> On identical machines, one with 9.1-RC2 and one with HEAD from yesterday
>> (GENERIC) I see the following in systat -v:
>> 9.1:
>> 65 cpu0:timer
>> 10 cpu1:timer
>> HEAD:
>> 1127 cpu0:timer
>> 22 cpu1:timer
>> These are Supermicro i3 boxes and as far as I can see they have matching
>> BIOS config.
>> Thanks,
>> J
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> Which is your refresh rate for systat?
> I generally measure sampling every one second (i.e. systat -vm 1).
> Also, are you making your measurements when the system is idle?
> In order to trace the source(s) of these interrupts you might consider
> to collect data via KTR.

I'm also using a one second refresh rate, the system is entirely idle 
and the interupt rate is almost entirely static at 1127, occasionally it 
will drop to 1119.

 From what I understand the timer is hz/ticks which became dynamic in 
9.0, although that behaviour doesn't appear to be in HEAD anymore, at 
least on this hardware.


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