lkml.org 
[lkml]   [2007]   [Jun]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
SubjectRe: [RFC] X86 SMP cpu enumeration changes
Date
From
As a followup to the message I posted earlier, I found that the  
following patch restores the old behavior of allowing maxcpus to
effectively turn off hyperthreading. In case you missed my earlier
message, in 2.6.16 through at least 2.6.19 using the maxcpus trick
will fail to use all of your physical cpus.

Although this patch works for me, I am quite sure that this patch is
unacceptable to folks using CPU hotplug, however. One alternative
would be to make the two lines of code in each location conditional
on CONFIG_HOTPLUG_CPU and !CONFIG_HOTPLUG_CPU respectively, but that
seems a little ugly.

Does anyone have a better fix?

I know my mailer smashes the patch, but this is intended for
discussion rather than application.

--- a/arch/i386/kernel/mpparse.c 2006-11-29 15:57:37.000000000
-0600
+++ b/arch/i386/kernel/mpparse.c 2007-06-06 16:41:06.635814335 -0500
@@ -180,9 +180,6 @@ static void __devinit MP_processor_info
}
apic_version[m->mpc_apicid] = ver;
- phys_cpu = apicid_to_cpu_present(apicid);
- physids_or(phys_cpu_present_map, phys_cpu_present_map,
phys_cpu);
-
if (num_processors >= NR_CPUS) {
printk(KERN_WARNING "WARNING: NR_CPUS limit of %i
reached."
" Processor ignored.\n", NR_CPUS);
@@ -195,6 +192,9 @@ static void __devinit MP_processor_info
return;
}
+ phys_cpu = apicid_to_cpu_present(apicid);
+ physids_or(phys_cpu_present_map, phys_cpu_present_map,
phys_cpu);
+
cpu_set(num_processors, cpu_possible_map);
num_processors++;


--
Mark Rustad, MRustad@gmail.com

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-06-07 00:21    [W:0.751 / U:0.164 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site