Topology aware scheduling algorithm.

David Xu davidxu at FreeBSD.org
Tue Feb 26 02:41:38 UTC 2008


Jeff Roberson wrote:
> Also in the cpuset.diff at:
> 
> http://people.freebsd.org/~jeff/cpuset.diff
> 
> There is support for cpu topology aware scheduling.  This allows the 
> scheduler to know which cores are colocated on packages and what the 
> cache arrangement between them is.
> 
> We have seen big improvements in some workloads and some reduction in 
> other workloads.  However, I believe this should finally close the gap 
> on the few benchmarks where ULE could trail 4BSD.  Please prove me wrong 
> if you can so I can continue to make ULE better.
> 
> Right now the MD code is slightly lagging behind what the scheduler can 
> utilize.  If you have an interest in digging through processor 
> documentation to write code to detect more information about the caches 
> please contact me.  I'd love some help.
> 
> This code and the cpusets will likely be committed to 8.0 by the end of 
> the week and then we'll discuss MFCs after some time to settle there.
> 
> Thanks,
> Jeff

FYI, sometimes ago, I have written some code to collect cpu topology
information according to vendor's specifications, it is only for x86.
each cpu just calls cpu_topology_update() at startup time, and the
information will be collected.

http://people.freebsd.org/~davidxu/sched/

note that these code have not been updated for AMD's 4-core
package yet, I have not this cpu.

Regards,
David Xu



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