Date: Mon, 9 Nov 2009 09:27:04 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Trever <anti_spamsys@yahoo.com> Subject: Re: Why is default value of NKPT so small? mfsroot Message-ID: <200911090927.05010.jhb@freebsd.org> In-Reply-To: <761362.20406.qm@web113204.mail.gq1.yahoo.com> References: <761362.20406.qm@web113204.mail.gq1.yahoo.com>
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On Friday 06 November 2009 2:19:51 pm Trever wrote: > Does anyone know what the thinking is behind the default value of NKTP in /usr/src/sys/i386/include/pmap.h? > > It seems to me that it's too small, though I'm wondering if there are some considerations in changing it's value that I should know about. > > Too small because: making it a little more than twice as large (so you can get about a 300MB mfsroot to boot) means you can (by default) boot a standard FreeBSD system into memory, and I know I can't be the only one who would value that a great deal for many reasons. As it stands you have to ax things out (like depenguinator does, for example). Or you have to recompile the kernel. > > Does it have to be like this? > > Which leads me to two more questions: > - is it possible to change the NKTP value without recompiling the kernel? I think there isn't but I'll ask. > - is it possible to change the NKTP value without editing pmap.h (can I pass a variable into the kernel build process)? I keep meaning to make NKPT a kernel option for i386. Try this patch, it should let you add 'options NKPT=xxx' to your kernel config. Index: conf/options.i386 =================================================================== --- conf/options.i386 (revision 198997) +++ conf/options.i386 (working copy) @@ -12,6 +12,7 @@ MAXMEM MPTABLE_FORCE_HTT MP_WATCHDOG +NKPT opt_pmap.h PERFMON PMAP_SHPGPERPROC opt_pmap.h POWERFAIL_NMI opt_trap.h Index: i386/i386/mp_machdep.c =================================================================== --- i386/i386/mp_machdep.c (revision 198997) +++ i386/i386/mp_machdep.c (working copy) @@ -30,6 +30,7 @@ #include "opt_cpu.h" #include "opt_kstack_pages.h" #include "opt_mp_watchdog.h" +#include "opt_pmap.h" #include "opt_sched.h" #include "opt_smp.h" Index: i386/xen/mp_machdep.c =================================================================== --- i386/xen/mp_machdep.c (revision 198997) +++ i386/xen/mp_machdep.c (working copy) @@ -31,6 +31,7 @@ #include "opt_cpu.h" #include "opt_kstack_pages.h" #include "opt_mp_watchdog.h" +#include "opt_pmap.h" #include "opt_sched.h" #include "opt_smp.h" -- John Baldwin
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