Re: smpnice: issues with finding busiest queue

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Siddha, Suresh B wrote:
On Thu, Apr 13, 2006 at 10:05:51AM +1000, Peter Williams wrote:
There be dragons here :-(.


At more places in this part of the world (smpnice) :)

We need to relook at find_busiest_queue()... With the current weighted
calculations, it doesn't always make sense to look at the highest weighted
runqueue in the busy group..

for example on a DP with HT system, how does the load balance behave with
Package-0 containing one high priority and one low priority, Package-1
containing one low priority(with other thread being idle)..

Package-1 thinks that it need to take the low priority thread from Package-0.
And find_busiest_queue() returns the cpu thread with highest priority task..
And ultimately(with help of active load balance) we move high priority
task to Package-1. And same continues with Package-0 now, moving high priority
task from package-1 to package-0..

Even without the presence of active load balance, load balance will fail
to balance(having two low priority tasks on one package, and high
priority task on another package) the above scenario....

We probably need to use imbalance(and more factors) to determine the busiest queue in the group.....

A patch would be nice.

--
Peter Williams                                   [email protected]

"Learning, n. The kind of ignorance distinguishing the studious."
 -- Ambrose Bierce
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux