Kern.hz= +1 hertz at anything 2500 and above.

Adrian Chadd adrian at freebsd.org
Thu Jul 25 16:11:39 UTC 2013


On 25 July 2013 02:51, Wojciech Puchar <wojtek at wojtek.tensor.gdynia.pl> wrote:
>> improved with a higher kern.hz rating. Unless the future holds an emu20k2,
>> there will be RAM used from the motherboard.
>> 1. I will need a real-time or a faster kernel- hence the high rate wanted-
>> because the devices to be built will be used in an active environment:
>> art,
>> music, audio control.
>> 2. Any system with limited memory and a low CPU hertz rate benefits from
>> the higher kern.hz setting.

> rather opposite. more kern.hz=more interrupts.

Right.

More hz == more interrupts and less ability for a CPU-bound process to
chew all the CPU.

So is it a scheduling issue, where you have multiple CPU bound
userland processes that aren't being fair and consuming all the CPU?
Is it that your device driver(s) aren't interrupting correctly,
relying on the hz tick to make up the slack, etc.

Is it a busted halt loop, which is being papered over with hz ticks?

Have you tried -10 on that kit, with the more aggressive clock/timer
code that won't interrupt unless it needs to? Has that changed things?



-adrian


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