Date: Thu, 02 Jun 2011 14:23:00 +0200 From: Ivan Voras <ivoras@freebsd.org> To: freebsd-current@freebsd.org Subject: Re: [PATCH] Add the infrastructure for supporting an infinite number of CPUs Message-ID: <is7vb4$q79$1@dough.gmane.org> In-Reply-To: <BANLkTi=xgP64i2S=SE1zz-p07b7cTA06Zg@mail.gmail.com> References: <BANLkTi=xgP64i2S=SE1zz-p07b7cTA06Zg@mail.gmail.com>
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On 01/06/2011 20:21, Attilio Rao wrote: > Current maximum number of CPUs supported by the FreeBSD kernel is 32. > That number cames from indirectly by the fact that we have a cpumask_t > type, representing a mask of CPUs, which is an unsigned int right now. > I then made a patch that removes the cpumask_t type and uses cpuset_t > type for characterizing a generic mask of CPUs: > http://www.freebsd.org/~attilio/largeSMP/largeSMP-patchset-beta-0.diff Hi, I'm just wandering: what is the expected overhead of this, compared to using a simple atomic integer (32-bit on i386, 64-bit on amd64)? I assume that this will introduce more work, like locking, in performance-critical code like the scheduler, etc.?
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