Re: [RFC] CPU hard limits

Chris Friesen
2009-06-05T14:44:31Z

Srivatsa Vaddagiri wrote:
> On Fri, Jun 05, 2009 at 01:53:15AM -0700, Paul Menage wrote:
>> This claim (and the subsequent long thread it generated on how limits
>> can provide guarantees) confused me a bit.
>>
>> Why do we need limits to provide guarantees when we can already
>> provide guarantees via shares?
>
> I think the interval over which we need guarantee matters here. Shares
> can generally provide guaranteed share of resource over longer (sometimes
> minutes) intervals. For high-priority bursty workloads, the latency in
> achieving guaranteed resource usage matters. By having hard-limits, we are
> "reserving" (potentially idle) slots where the high-priority group can run and
> claim its guaranteed share almost immediately.

Why do you need to "reserve" it though? By definition, if it's
high-priority then it should be able to interrupt the currently running
task.

Chris