Re: 2.4.10pre7aa1

Dipankar Sarma
2001-09-11T12:17:38Z

In article <20010911135735.T715@athlon.random> you wrote:
> On Tue, Sep 11, 2001 at 05:23:01PM +0530, Dipankar Sarma wrote:
>> In article <20010911131238.N715@athlon.random> you wrote:
>> > many thanks. At the moment my biggest concern is about the need of
>> > call_rcu not to be starved by RT threads (keventd can be starved so then
>> > it won't matter if krcud is RT because we won't start using it).
>>
>> > Andrea
>>
>> I think we can avoid keventd altogether by using a periodic timer (say 10ms)
>> to check for completion of an RC update. The timer may be active
>> only if only if there is any RCU going on in the system - that way
>> we still don't have any impact on the rest of the kernel.

> the timer can a have bigger latency than keventd calling wait_for_rcu
> so it should be a loss in a stright bench with light load, but OTOH we
> only care about getting those callbacks executed eventually and the
> advantage I can see is that the timer cannot get starved.

> Andrea

What kind of timer latencies are we talking about ? I would not be
too concerned if the RCU timers execute in 40ms instead of requested
10ms. The question is are there situations where they can get delayed
by minutes ?

Thanks
Dipankar
--
Dipankar Sarma <dipankar@in.ibm.com> Project: http://lse.sourceforge.net
Linux Technology Center, IBM Software Lab, Bangalore, India.