jdk and NUMA

David Dabbs dmdabbs at gmail.com
Thu Sep 9 12:04:45 PDT 2010

My apologies if this is not the correct place for this question.

I have a shiny new NUMA-capable Xeon server and want to ensure that my Java
app(s) make full use of the hardware.
So, I ran java (jdk 6u21) -XX:+PrintFlagsFinal and (naively) expected to see
UseNUMA := true but did not.

I found this post


If its simply a matter of turning it on that's what I'll do. Any guidelines
about use of mumactl or the jdks NUMA "knobs"?

uname -a
Linux 2.6.18-128.7.1.el5 #1 SMP Mon Aug 24 08:21:56 EDT 2009 x86_64 x86_64
x86_64 GNU/Linux

Linux, CentOS 5

cat /proc/cpuinfo

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 26
model name      : Intel(R) Xeon(R) CPU           E5530  @ 2.40GHz
stepping        : 5
cpu MHz         : 2394.112
cache size      : 8192 KB
physical id     : 1
siblings        : 8
core id         : 0
cpu cores       : 4
apicid          : 16
fpu             : yes
fpu_exception   : yes
cpuid level     : 11
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm syscall nx rdtscp
lm constant_tsc ida nonstop_tsc pni monitor ds_cpl vmx est tm2 cx16 xtpr
popcnt lahf_lm
bogomips        : 4791.64
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: [8]        

This repeats for processors 1-15.

Two physical ids, 0,1.

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