CentOS - Jul 2013 - Cpus_allowed_list issue in RHEL6.4

Hi All,

I am using RHEL 6.4 on a Dell Server with 32 cores.

But in the Cpus_allowed_list only 30 cores are available. Why is that?

See the snippet from cat /proc/self/status:
Cpus_allowed:   7fff7fff
Cpus_allowed_list:      0-14,16-30


The allowed list is same for the init process as well (see below).
I didn't see this issue, in RHEL 6.2.

Why is that? Is there a way to change it?

-miraj

-------------------------------------
[root at localhost bin]# uname -a
Linux localhost 2.6.32-358.el6.x86_64 #1 SMP Tue Jan 29 11:47:41 EST 2013 x86_64
x86_64 x86_64 GNU/Linux
[root at localhost bin]#
[root at localhost bin]#
[root at localhost bin]# cat /proc/1/status
Name:   init
State:  S (sleeping)
Tgid:   1
Pid:    1
PPid:   0
TracerPid:      0
Uid:    0       0       0       0
Gid:    0       0       0       0
Utrace: 0
FDSize: 64
Groups:
VmPeak:    19364 kB
VmSize:    19356 kB
VmLck:         0 kB
VmHWM:      1544 kB
VmRSS:      1544 kB
VmData:      328 kB
VmStk:        88 kB
VmExe:       140 kB
VmLib:      2348 kB
VmPTE:        52 kB
VmSwap:        0 kB
Threads:        1
SigQ:   1/256326
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000001000
SigCgt: 00000001a0016623
CapInh: 0000000000000000
CapPrm: ffffffffffffffff
CapEff: fffffffffffffeff
CapBnd: ffffffffffffffff
Cpus_allowed:   7fff7fff
Cpus_allowed_list:      0-14,16-30
Mems_allowed:  
00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000003
Mems_allowed_list:      0-1
voluntary_ctxt_switches:        1603
nonvoluntary_ctxt_switches:     62

Read up on CPU sets

http://man7.org/linux/man-pages/man5/proc.5.html

http://man7.org/linux/man-pages/man7/cpuset.7.html 

Tony.

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On
Behalf Of Miraj Mohamed
Sent: 24 July 2013 11:57
To: centos at centos.org
Subject: [CentOS] Cpus_allowed_list issue in RHEL6.4


Hi All,

I am using RHEL 6.4 on a Dell Server with 32 cores.

But in the Cpus_allowed_list only 30 cores are available. Why is that?

See the snippet from cat /proc/self/status:
Cpus_allowed:   7fff7fff
Cpus_allowed_list:      0-14,16-30


The allowed list is same for the init process as well (see below).
I didn't see this issue, in RHEL 6.2.

Why is that? Is there a way to change it?

-miraj

-------------------------------------
[root at localhost bin]# uname -a
Linux localhost 2.6.32-358.el6.x86_64 #1 SMP Tue Jan 29 11:47:41 EST 2013 x86_64
x86_64 x86_64 GNU/Linux [root at localhost bin]# [root at localhost bin]# [root
at localhost bin]# cat /proc/1/status
Name:   init
State:  S (sleeping)
Tgid:   1
Pid:    1
PPid:   0
TracerPid:      0
Uid:    0       0       0       0
Gid:    0       0       0       0
Utrace: 0
FDSize: 64
Groups:
VmPeak:    19364 kB
VmSize:    19356 kB
VmLck:         0 kB
VmHWM:      1544 kB
VmRSS:      1544 kB
VmData:      328 kB
VmStk:        88 kB
VmExe:       140 kB
VmLib:      2348 kB
VmPTE:        52 kB
VmSwap:        0 kB
Threads:        1
SigQ:   1/256326
SigPnd: 0000000000000000
ShdPnd: 0000000000000000
SigBlk: 0000000000000000
SigIgn: 0000000000001000
SigCgt: 00000001a0016623
CapInh: 0000000000000000
CapPrm: ffffffffffffffff
CapEff: fffffffffffffeff
CapBnd: ffffffffffffffff
Cpus_allowed:   7fff7fff
Cpus_allowed_list:      0-14,16-30
Mems_allowed:  
00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000000,00000003
Mems_allowed_list:      0-1
voluntary_ctxt_switches:        1603
nonvoluntary_ctxt_switches:     62

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