Date: Sat, 1 Mar 2003 20:06:15 -0600 From: Juli Mallett <jmallett@FreeBSD.org> To: Hiten Pandya <hiten@unixdaemons.com> Cc: current@FreeBSD.org Subject: Re: Possible patch for limiting APs at startup Message-ID: <20030301200615.A63428@FreeBSD.org> In-Reply-To: <20030302015353.GA68661@unixdaemons.com>; from hiten@unixdaemons.com on Sat, Mar 01, 2003 at 08:53:53PM -0500 References: <20030302015353.GA68661@unixdaemons.com>
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* De: Hiten Pandya <hiten@unixdaemons.com> [ Data: 2003-03-01 ]
[ Subjecte: Possible patch for limiting APs at startup ]
> Hello.
>
> Just as the topic says, do you think this patch is good enough, or gets
> even close to it? I have tested the patch, and it seems to do it's job
> in the right way. Some might call it hackery, but it's better than
> nothing I would suppose.
I think your use of "cpus" to refer to APs only is silly, and also that
overriding mp_naps instead of using a real cpus value and using it as
a bounds check akin to MAXCPU, is a bit of the wrong direction. As you
know, the following is my patch, and it does not work, but I think,
personally, the behaviour is saner, in theory at least :)
%%%
Index: mp_machdep.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/i386/mp_machdep.c,v
retrieving revision 1.203
diff -d -c -r1.203 mp_machdep.c
*** mp_machdep.c 24 Feb 2003 14:36:03 -0000 1.203
--- mp_machdep.c 2 Mar 2003 00:22:58 -0000
***************
*** 249,254 ****
--- 249,259 ----
/** XXX FIXME: what system files declare these??? */
extern struct region_descriptor r_gdt, r_idt;
+ int mp_maxcpus = 0; /* max CPUs; not in BSS so it can be hacked. */
+ TUNABLE_INT("machdep.smp_max_cpus", &mp_maxcpus);
+ SYSCTL_INT(_machdep, OID_AUTO, smp_max_cpus, CTLFLAG_RD,
+ &mp_maxcpus, 1, "Maximum number of CPUs to use.");
+
int bsp_apic_ready = 0; /* flags useability of BSP apic */
int mp_naps; /* # of Applications processors */
int mp_nbusses; /* # of busses */
***************
*** 864,874 ****
}
}
! /* qualify the numbers */
! if (mp_naps > MAXCPU) {
printf("Warning: only using %d of %d available CPUs!\n",
! MAXCPU, mp_naps);
! mp_naps = MAXCPU;
}
/* See if we need to fixup HT logical CPUs. */
--- 869,881 ----
}
}
! /* use the smallest number of requested CPUs or CPUs we support. */
! if ((mp_maxcpus > 0 && mp_naps > mp_maxcpus) || mp_naps > MAXCPU) {
! if (mp_maxcpus <= 0)
! mp_maxcpus = MAXCPU;
printf("Warning: only using %d of %d available CPUs!\n",
! mp_maxcpus, mp_naps);
! mp_naps = mp_maxcpus;
}
/* See if we need to fixup HT logical CPUs. */
%%%
Thanx,
juli.
--
Juli Mallett <jmallett@FreeBSD.org> - AIM: BSDFlata -- IRC: juli on EFnet
OpenDarwin, Mono, FreeBSD Developer - ircd-hybrid Developer, EFnet addict
FreeBSD on MIPS-Anything on FreeBSD - /* XXX Nothing to see here, now. */
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