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Date: Sat, 24 Dec 2011 01:02:40 +0200
From: Andriy Gapon <avg@FreeBSD.org>
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To: Adrian Chadd <adrian@FreeBSD.org>
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Cc: freebsd-stable@FreeBSD.org, Steve Kargl <sgk@troutmask.apl.washington.edu>
Subject: Re: SCHED_ULE should not be the default
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on 24/12/2011 00:49 Adrian Chadd said the following:
> Does ULE care (much) if the nodes are hyperthreading or real cores?
> Would that play a part in what it tries to schedule/spread?

An answer to this part from the theory.
ULE does care about physical topology of the (logical) CPUs.
So, for example, four cores are not the same as two core with two hw threads
from ULE's perspective.  Still, ULE tries to eliminate any imbalances between
the CPU groups starting from the top level (e.g. CPU packages in a multi-socket
system) and all the way down to the individual (logical) CPUs.
Thus, given enough load (L >= N) there should not be an idle CPU in the system
whatever the topology.  Modulo bugs, of course, as always.

-- 
Andriy Gapon