Skip site navigation (1)Skip section navigation (2)
Date:      Mon, 29 Aug 2011 23:56:48 +0100
From:      RW <rwmaillists@googlemail.com>
To:        freebsd-questions@freebsd.org
Subject:   Re: Turn off hyperthreading on dual core Atom?
Message-ID:  <20110829235648.74676b61@gumby.homeunix.com>
In-Reply-To: <201108292115.PAA21491@lariat.net>
References:  <201108291724.LAA18734@lariat.net> <4E5BEE9C.7080706@cran.org.uk> <201108292115.PAA21491@lariat.net>

next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, 29 Aug 2011 15:15:02 -0600
Brett Glass wrote:

> At 01:55 PM 8/29/2011, Bruce Cran wrote:
> 
> >Actually, the ULE scheduler does know about HyperThreading and the 
> >topology of such CPUs. I don't know what it does with the 
> >information, but it probably works to optimize cache usage etc.
> 
> Alas, during a recent kernel build, I used the -j2 command line 
> option in "make" and watched as the scheduler repeatedly assigned 
> two instances of cc (the most CPU-intensive program) to the same core.

Doesn't that make sense. If the scheduler can't put two threads from
the same process on a core, it puts two processes running in the same
binary.

BTW I thought hyperthreading was off by default on security grounds.



Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20110829235648.74676b61>