[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Xen 3.4.1 NUMA support
On Mon, Nov 9, 2009 at 11:39 AM, Dulloor <dulloor@xxxxxxxxx> wrote: > What's the current scope and status of your scheduler work ? Is it > going to look similar to the Linux scheduler (with scheduling domains, > et al). In that case, topology is already accounted for, to a large > extent. It would be good to know so that I can work on something that > doesn't overlap. My plan was to do something similar to Linux, but with this difference: Instead of having one runqueue per logical processor (as both Xen and Linux currently do), and having "domains" all the way up (as Linux currently does), I had planned on having one runqueue per L2 processor cache. The main reason to avoid migration is to preserve a warm cache; but since L1's are replaced so quickly, there should be little impact to a VM migrating between different threads and cores which share the same L2. Above the L2s I was planning on having an idea similar to the Linux "domains" (although obviously it would need a different name to avoid confusion), and doing explicit load-balancing between them. But as I have not had a chance to test this kind of load balancing yet, the plan may change somewhate before then. Problems to solve wrt NUMA, as I understand it, are to balance the performance cost of sharing a busy local CPU, vs the performance cost of non-local memory accesses. This would involve adding the NUMA logic to the load balancing algorithm. Which I guess would depend in part on having a load balancing algorithm to begin with. :-) Once I have the basic credit patches in working order, would you be interested in working on the load-balancing between runqueues? I can then work on further testing of the credit algorithm. My ultimate goal would be to have a basic regression test that people could use to measure how their changes to the scheduler affect a wide variety of workloads. -George _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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