Date: Mon, 19 Dec 2011 23:22:40 +0200 From: Andriy Gapon <avg@FreeBSD.org> To: Nathan Whitehorn <nwhitehorn@FreeBSD.org> Cc: freebsd-performance@FreeBSD.org, freebsd-current@FreeBSD.org Subject: Re: SCHED_ULE should not be the default Message-ID: <4EEFAB20.4070300@FreeBSD.org> In-Reply-To: <4EEF5D5A.5050700@freebsd.org> References: <4EE1EAFE.3070408@m5p.com> <4EE22421.9060707@gmail.com> <4EE6060D.5060201@mail.zedat.fu-berlin.de> <4EE69C5A.3090005@FreeBSD.org> <20111213104048.40f3e3de@nonamehost> <20111213090051.GA3339@vniz.net> <4EED5200.20302@cran.org.uk> <20111218164924.L64681@sola.nimnet.asn.au> <20111218075241.GA45367@vniz.net> <20111218102401.GA42627@freebsd.org> <20111218102600.GA44118@freebsd.org> <CAJ-VmomJ9D63xYyg4udKu1FnihVworgp8MrxzXwpG2XVZww8DA@mail.gmail.com> <4EEF5D5A.5050700@freebsd.org>
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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
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