>Number: 190169
>Category: kern
>Synopsis: Increase MAXCPU on amd64 systems
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Sat May 24 10:30:00 UTC 2014
>Closed-Date:
>Last-Modified:
>Originator: Tim Bishop
>Release: FreeBSD 11.0-CURRENT amd64
>Organization:
>Environment:
System: FreeBSD buzzard 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r266603M: Sat May
24 03:25:35 BST 2014 tdb@buzzard:/usr/obj/usr/src/sys/GENERIC amd64
4x Intel(R) Xeon(R) CPU E7-4830 v2 @ 2.20GHz (2200.05-MHz K8-class CPU)
This gives 40 cores with a total of 80 threads.
>Description:
In param.h MAXCPU is set to 64. This results in 16 of the
80 threads being disabled at boot time, and errors like:
FreeBSD/SMP: Multiprocessor System Detected: 64 CPUs
FreeBSD/SMP: 3 package(s) x 10 core(s) x 2 SMT threads
cpu0 (BSP): APIC ID: 0
cpu1 (AP): APIC ID: 1
...
cpu62 (AP): APIC ID: 98
cpu63 (AP): APIC ID: 99
cpu (AP): APIC ID: 100 (disabled)
cpu (AP): APIC ID: 101 (disabled)
cpu (AP): APIC ID: 102 (disabled)
cpu (AP): APIC ID: 103 (disabled)
cpu (AP): APIC ID: 104 (disabled)
cpu (AP): APIC ID: 105 (disabled)
cpu (AP): APIC ID: 112 (disabled)
cpu (AP): APIC ID: 113 (disabled)
cpu (AP): APIC ID: 114 (disabled)
cpu (AP): APIC ID: 115 (disabled)
cpu (AP): APIC ID: 116 (disabled)
cpu (AP): APIC ID: 117 (disabled)
cpu (AP): APIC ID: 118 (disabled)
cpu (AP): APIC ID: 119 (disabled)
cpu (AP): APIC ID: 120 (disabled)
cpu (AP): APIC ID: 121 (disabled)
WARNING: Non-uniform processors.
WARNING: Using suboptimal topology.
>How-To-Repeat:
Boot any recent FreeBSD version, including HEAD, on a system
with more than 64 CPU cores/threads.
>Fix:
The current top end processors have 15 cores and 30 threads.
So a quad socket system would have a total of 120 threads.
I believe this should be supported in GENERIC so FreeBSD
works out of the box. The patch below does this.
It'd be nice to see this MFCed to stable/10 so it makes the
10.1 release. It'd be even nicer to see it MFCed to stable/9
for 9.3, but I suspect it'll be too late for that.
For what it's worth I tested the most recent Ubuntu release
and it detected all the threads out of the box.
Some consideration should also be given to kern/185831. It
has been committed but I don't think it has been MFCed yet.
I can confirm that I don't receive any panic on HEAD with
MAXCPU set to 128 and with witness enabled.
--- diff begins here ---
Index: sys/amd64/include/param.h
===================================================================
--- sys/amd64/include/param.h (revision 266603)
+++ sys/amd64/include/param.h (working copy)
@@ -65,7 +65,7 @@
#if defined(SMP) || defined(KLD_MODULE)
#ifndef MAXCPU
-#define MAXCPU 64
+#define MAXCPU 128
#endif
#else
#define MAXCPU 1
--- diff ends here ---
>Release-Note:
>Audit-Trail:
>Unformatted:
_______________________________________________
freebsd-bugs@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-bugs
To unsubscribe, send any mail to "freebsd-bugs-unsubscr...@freebsd.org"
