Date: Sun, 8 Oct 2006 07:45:19 -0500 From: Astrodog <astrodog@gmail.com> To: "LI Xin" <delphij@delphij.net> Cc: freebsd-current@freebsd.org, David Xu <davidxu@freebsd.org>, current@freebsd.org Subject: Re: [PATCH] MAXCPU alterable in kernel config - needs testers Message-ID: <2fd864e0610080545m1038d560o74767d775d0ad26b@mail.gmail.com> In-Reply-To: <4528F069.7040504@delphij.net> References: <2fd864e0610080423q7ba6bdeal656a223e662a5d@mail.gmail.com> <200610082011.53649.davidxu@freebsd.org> <2fd864e0610080516k6682c101i8d9b83578593fb28@mail.gmail.com> <4528F069.7040504@delphij.net>
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On 10/8/06, LI Xin <delphij@delphij.net> wrote: > Astrodog wrote: > > On 10/8/06, David Xu <davidxu@freebsd.org> wrote: > >> On Sunday 08 October 2006 19:23, Astrodog wrote: > >> > With the quad core processors coming out soon, this is going to become > >> > more of an issue.. (Sun T1/2000s aside). This is basically the same > >> > patch from a few months ago, with updated offsets. > >> > > >> > If you don't define MAXCPU in the kernel config, it reverts to old > >> > behavior. It has no logic to keep you from shooting yourself in the > >> > foot though.. you can define options SMP and options MAXCPU 128 on > >> > arm. > >> > > >> > --- Harrison Grundy > >> > >> I think MAXCPU should not be great than 32, since we currently define > >> cpumask_t as an integer which now should be changed to a bitmap and > >> a group of operations like we did for sigset_t. > >> > >> David Xu > >> > > > > Currently, MAXCPU is 16 on most platforms. > > In general, this value serves as a boundary of the kernel logic, and is > determined by various factors, e.g., the bits available in cpumask_t, > etc., therefore, I really do not see much benefit of letting this value > customizable. > > Perhaps we can say that the problem is not that the value itself is > immutable by the system administrator, but it was (perhaps?) not > correctly reflected the actual support that the kernel can provide? > Perhaps the way to handle this, then, is to only allow it to be set lower. --- Harrison
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