Date: Fri, 8 Jul 2011 11:14:36 -0700 From: Peter Wemm <peter@wemm.org> To: John Baldwin <jhb@freebsd.org> Cc: Kostik Belousov <kostikbel@gmail.com>, Attilio Rao <attilio@freebsd.org>, Sergey Kandaurov <pluknet@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: [PATCH] Add MAXCPU as a kernel config option and quality discussion on this Message-ID: <CAGE5yCq1B7LZgQOAV2FjNF6kBoGUf_ug7FdpEO3jb%2Berj73CvA@mail.gmail.com> In-Reply-To: <CAGE5yCocUvyyNzsMPO8vB4QrBdYEzM=%2BpkPCq8gBHEPu3ypjzA@mail.gmail.com> References: <CAJ-FndDZu0cBrVbH3W%2B8Tj86T5h%2BwwWqUVnjJO1rtXopKodNOA@mail.gmail.com> <20110708164844.GZ48734@deviant.kiev.zoral.com.ua> <201107081314.44128.jhb@freebsd.org> <CAGE5yCocUvyyNzsMPO8vB4QrBdYEzM=%2BpkPCq8gBHEPu3ypjzA@mail.gmail.com>
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On Fri, Jul 8, 2011 at 10:56 AM, Peter Wemm <peter@wemm.org> wrote: > On Fri, Jul 8, 2011 at 10:14 AM, John Baldwin <jhb@freebsd.org> wrote: >> On Friday, July 08, 2011 12:48:44 pm Kostik Belousov wrote: >>> On Fri, Jul 08, 2011 at 05:37:17PM +0200, Attilio Rao wrote: >>> > I've made this patch for making MAXCPU a kernel config option: >>> > http://www.freebsd.org/~attilio/maxcpu_kernel_opt.diff >>> > >>> > Besides if this is a good idea or not (which I think it is) I want to >>> > discuss this implementation and similar related problems. >>> > In this case I've been forced to include opt_maxcpu.h in all the MD >>> > param.h implementations. A similar case, KSTACK_PAGES, includes the >>> > opt_kstack_pages.h only in the consumers. While this is possible for >>> > KSTACK_PAGES, because there are very little consumers, it would be >>> > impratical for MAXCPU. Besides, this is a very dangerous practice >>> > IMHO: if a consumer fails to add opt_kstack_pages it may end up with a >>> > faulty value, introducing a breakage that would go unnoticed. >>> > >>> > In my case, I think that including opt_maxcpu is a viable panacea, but >>> > in general, after discussing with peter@, probabilly the better idea >>> > would be having a centralized script that does pre-processing before >>> > to start compiling and set with the right values all those constants >>> > (something like genassym.c, but of course with a different purpose). >>> > >>> > What are your ideas on that? Do you think that including opt_maxcpu.h >>> > would be acceptable for the time being? >>> >>> I vote for putting MAXCPU in opt_global.h. >>> Why did you choosed separate opt header ? >> >> I agree this should just go into opt_global.h. > > I disagree. That makes it even harder to track down KLD's that depend > on the correct value of MAXCPU. Ahh crap. I forgot about this: #ifdef _KERNEL #define CPU_SETSIZE MAXCPU #endif MAXCPU does have to be in opt_global.h and potentially affects kernel modules. -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6FJV "All of this is for nothing if we don't go to the stars" - JMS/B5 "If Java had true garbage collection, most programs would delete themselves upon execution." -- Robert Sewell
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