Date: Wed, 28 May 2014 10:51:28 -0700 From: Adrian Chadd <adrian@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: Attilio Rao <attilio@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, Jia-Shiun Li <jiashiun@gmail.com>, Alan Somers <asomers@freebsd.org>, Tim Bishop <tim-lists@bishnet.net> Subject: Re: Processor cores not properly detected/activated? Message-ID: <CAJ-VmomGgJGFO5yM6F4n8JVmBiDg2DD8zOc8VKyorf-xgLAGvg@mail.gmail.com> In-Reply-To: <201405280956.27800.jhb@freebsd.org> References: <20140524014713.GF13462@carrick-users.bishnet.net> <20140524103835.GI13462@carrick-users.bishnet.net> <CAHNYxxPAqrRcJyxY8ZDnL87FdRAUxBL522nAAEQpA19uByYE2w@mail.gmail.com> <201405280956.27800.jhb@freebsd.org>
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On 28 May 2014 06:56, John Baldwin <jhb@freebsd.org> wrote: > Userland cpusets only default to 128 (CPU_MAXSIZE in <sys/_cpuset.h>). > Changing MAXCPU to even 128 is unfortunately a potential KBI change since it > changes the size of 'cpuset_t'. We can certainly bump these in HEAD for 11, > but we might not be able to MFC them without introducing ABI breakage. > (The cpuset APIs do allow the size of cpuset_t to change as the size is > encoded in the API calls, so there is that, it's more that if some public > structure embeds a cpuset_t in the kernel that we would have problems. I > thought 'struct pcpu' did, but it does not.) > > Hmm, smp_rendezvous() accepts a cpuset_t as its first argument (and is a > public symbol used by kernel modules such as dtrace). 'struct rmlock' also > embeds a cpuset_t. So, I think we can't bump cpuset_t without breaking > the KBI. We can bump it in HEAD however. (Note, if re@ signed off, we could > perhaps merge to 10, but we tend to be very hesitant about breaking the KBI.) > One thing we could do safely is bump the userland cpuset size to 256 in 10. > It's really only MAXCPU that is problematic. > > In particular, I propose we bump the userland cpuset_t size to 256 now (and > go ahead and merge that to 10). In HEAD only we can bump MAXCPU for amd64 > to 256. Since 11 is going to be around for a few years, can we experiment bumping it up to something compute-cluster-computer-sized just to get it over with? Something stupid, like 4096 or something? -a
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