Date: Mon, 27 Sep 2004 12:40:21 -0700 From: Julian Elischer <julian@elischer.org> To: Petri Helenius <pete@he.iki.fi> Cc: Dave Dolson <ddolson@sandvine.com> Subject: Re: "Kernel Hacking"/Developing on a HT CPU versus "physical" CPUs Message-ID: <41586CA5.8030601@elischer.org> In-Reply-To: <415854C7.4040502@he.iki.fi> References: <A8535F8D62F3644997E91F4F66E341FC4063EC@exchange.sandvine.com> <15450.148.104.5.33.1096302710.squirrel@webmail.cs.columbia.edu> <415854C7.4040502@he.iki.fi>
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Petri Helenius wrote: > mre2007@cs.columbia.edu wrote: > >> Dave: >> >> yes this makes sense! So, does the scheduler take this into >> consideration? >> >> >> > The _ULE scheduler does, the _4BSD scheduler does not. not quite.. there is a small sysctl that will try make it select a processor on an idle die when selecting which idle cpu to wake up next.. but it's turned off by default and it doesn;t seem to make much difference.. (It' s also a hack because it's hard-wired for 2vcpus /die).. it is more a proff of concept hack.. (which is why it is turned off)) > > > Pete > >> -Marc >> >> >> >>> Here is one example: >>> If you have dual HT processors, this looks like 4 CPUs to the O/S. >>> For performance reasons, the scheduler should not treat them equally. >>> If there are two threads to run, they should be put on different >>> physical >>> processors (vs. two hyperthreads of the same processor). >>> >>> >>> David Dolson (ddolson@sandvine.com, www.sandvine.com) >>> >>> >>> >>> >>>> -----Original Message----- >>>> From: owner-freebsd-smp@freebsd.org >>>> [mailto:owner-freebsd-smp@freebsd.org]On Behalf Of >>>> mre2007@cs.columbia.edu >>>> Sent: Saturday, September 25, 2004 10:48 AM >>>> To: freebsd-smp@freebsd.org >>>> Subject: "Kernel Hacking"/Developing on a HT CPU versus >>>> "physical" CPUs >>>> >>>> >>>> Hey, I was wondering if from a developing/"kernel hacking" >>>> standpoint, are >>>> hyperthreading and two "physical" CPUs any different? At what >>>> point do the >>>> differences have to be taken into consideration when working on the >>>> FreeBSD kernel/scheduler/etc? I'm looking to start contributing to the >>>> FreeBSD project and am trying to get some hardware set aside. >>>> >>>> Thanks! >>>> -Marc >>>> _______________________________________________ >>>> freebsd-smp@freebsd.org mailing list >>>> http://lists.freebsd.org/mailman/listinfo/freebsd-smp >>>> To unsubscribe, send any mail to "freebsd-smp-unsubscribe@freebsd.org" >>>> >>>> >>> >> _______________________________________________ >> freebsd-smp@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-smp >> To unsubscribe, send any mail to "freebsd-smp-unsubscribe@freebsd.org" >> >> > > _______________________________________________ > freebsd-smp@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-smp > To unsubscribe, send any mail to "freebsd-smp-unsubscribe@freebsd.org"home | help
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