Date: Wed, 02 Jan 2002 00:05:56 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Steve Shorter <steve@nomad.lets.net> Cc: freebsd-hackers@freebsd.org Subject: Re: kernel panic on boot with 4G RAM Message-ID: <3C32BF64.60DCA8A4@mindspring.com> References: <20020101165106.A80908@nomad.lets.net> <3C3231B8.38C5A741@mindspring.com> <20020101191435.A80969@nomad.lets.net>
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Steve Shorter wrote: > > You really need to change the allocation of swap page descriptors > > in /sys/i386/machdep.c (among other things). > > Is this a trivial change? I don't know much about > FreeBSD kernel internals but can edit source with some guidance OR > can these changes be effected in the kernel config? No, but it was discussed in detail on the FreeBSD-current list last month, so your best bet would be to look there. > How about changing NKPT in sys/i386/include/pmap.h to > something bigger? .. like 60? No. The scaling would be too large. By default, the amount of page mapings is ~200M. This can be grown automatically by the kernel routines, so don't worry about it. The problem is that with that much memory, you will suck up more page tables than can possibly be used, since you can only map 4G, and the value does not asymptotically approach that, if you use the unchanged machdep.c. Matt Dillon posted a patch that makes the values more reasonably autosized based on physical memory size, but is not perfect (it can't be, for reasons discussed in the thread that I've already referred you to, above). > What "other things" should be done to tune a high memory > machine, or to get it to boot. Read the thread. We all spent a lot of time typing it. It's a fairly exhastive listing of what should/can be tuned. > > I personally suggest compiling your kernel with 3G KVA/1G User, > > instead of the default of 1G KVA/3G User. > > > > Ok. This can be done with > > options KVA_PAGES=768 Depends on what FreeBSD version you are running. You are posting to the -hackers list and not the -current or -stable list, so you will probably also have to adjust the kernbase address in the /sys/conf/ldscript.i386, as well. As I said before, look at the handbook, though it is somewhat incomplete. > What about the other KVA stuff in kernel config > > options VM_BCACHE_SIZE_MAX= > > The comments in LINT mention that this is capped at 260M > "effecting > 1G of ram". Should this be increased with machines with 4G? Depends. You are probably more worried about having mbufs, not FS bufs, which are allocated out of a totally seperate pool, not the buffer cache. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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