Re: SCHED_ULE should not be the default

From: Andriy Gapon <avg_at_FreeBSD.org>
Date: Mon, 19 Dec 2011 23:22:40 +0200
on 19/12/2011 17:50 Nathan Whitehorn said the following:
> The thing I've seen is that ULE is substantially more enthusiastic about
> migrating processes between cores than 4BSD.

Hmm, this seems to be contrary to my theoretical expectations.  I thought that
with 4BSD all threads that were not in one of the following categories:
- temporary pinned
- bound to cpu in kernel via sched_bind
- belong to a cpu set which a strict subset of a total set
were placed onto a common queue that was shared by all cpus.  And as such I
expected them to get picked up by the cpus semi-randomly.

In other words, I thought that it was ULE that took into account cpu/cache
affinities while 4BSD was deliberately entirely ignorant of those details.

-- 
Andriy Gapon
Received on Mon Dec 19 2011 - 20:22:47 UTC

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