Date: Sat, 20 Dec 2008 15:53:06 -0500 From: michael <michael.copeland@gmail.com> To: Brett Glass <brett@lariat.net> Cc: freebsd-questions@freebsd.org Subject: Re: Status of hyperthreading in FreeBSD Message-ID: <494D5B32.50806@gmail.com> In-Reply-To: <200812202039.NAA10290@lariat.net> References: <200812202039.NAA10290@lariat.net>
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Brett Glass wrote: > "Netbooks" based on Intel's "Atom" microprocessor are turning into big > hits this Christmas season. The Atom, a super-low-power x86 processor, > is an "in-order" machine, which means that except for a few special > cases it can spend a lot of time waiting for data to arrive when it > encounters a cache miss. So, hyperthreading may make sense on this > kind of processor as compared to one with out-of-order execution. > > Which raises a question: What's the status of FreeBSD's support for > hyperthreading? As far as I know, after it was revealed that some > processes on a machine with hyperthreading could "spy" on others, and > also that hyperthreading didn't always improve performance on high end > processors, the feature was turned off by default. But on single-user > machines, or on servers where the CPU was likely to be shared by two > processes that were both privileged anyway, it might make sense to > re-enable it. But has this feature of the scheduler been maintained > well enough for this to be a good idea? If not, would it worth looking > into updating it so that FreeBSD runs well on the Atom? > > --Brett Glass > as far as i know, just enabling smp will allow ht to function. also, i don't know if intel changed ht in the new atom processor, they could have. > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org"
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