RE: [Xen-users] Xen 3.3.0 cpu cache problems

["Robert Dunkley" <Robert@xxxxxxxxx>]

This is a known problem ,there is a CPUID fix floating around that you apply to the VM config file. Alternatively upgrading to Xen 3.3.1 should fix the problem.

 

Rob

---

From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx on behalf of Marcus Hall
Sent: Mon 02/02/2009 15:47
To: xen-users@xxxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Xen 3.3.0 cpu cache problems

Dear Xen users,

I have a problem with "Xen 3.3.0". All domU (paravirt) only have "32 KB"
of cache instead of "6144 KB" as listed in dom0. This is really
noticeable under load since the system tends to be really slow.

I did not have this problem with "Xen 3.2.1".

I'm using the same domU configuration files for the new and the old
installation.

Look at the field, cache size.

*"cat /proc/cpuinfo" under dom0.*

processor    : 0
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5420  @ 2.50GHz
stepping    : 10
cpu MHz        : 2493.748
cache size    : 6144 KB
physical id    : 0
siblings    : 1
core id        : 0
cpu cores    : 1
fpu        : yes
fpu_exception    : yes
cpuid level    : 13
wp        : yes
flags        : fpu de tsc msr pae cx8 apic sep mtrr cmov pat clflush
acpi mmx fxsr sse sse2 ss ht syscall nx lm constant_tsc pni est ssse3
cx16 lahf_lm
bogomips    : 4989.52
clflush size    : 64
cache_alignment    : 64
address sizes    : 38 bits physical, 48 bits virtual
power management:
*
"cat /proc/cpuinfo" under domU.*

processor    : 0
vendor_id    : GenuineIntel
cpu family    : 6
model        : 23
model name    : Intel(R) Xeon(R) CPU           E5420  @ 2.50GHz
stepping    : 10
cpu MHz        : 2493.748
cache size    : 32 KB
physical id    : 0
siblings    : 1
core id        : 0
cpu cores    : 1
fpu        : yes
fpu_exception    : yes
cpuid level    : 13
wp        : yes
flags        : fpu de tsc msr pae cx8 apic sep cmov pat clflush acpi mmx
fxsr sse sse2 ss ht syscall nx lm constant_tsc pni ssse3 cx16 lahf_lm
bogomips    : 4992.45
clflush size    : 64
cache_alignment    : 64
address sizes    : 38 bits physical, 48 bits virtual
power management:

*domU config file:*

kernel = "/etc/xen/kernel/vmlinuz-2.6.21-xen-domU"
builder='linux'
memory = 3072
name = "host1"
cpus = "0-2"
vcpus = 3
vif = [ 'mac=xx:xx:xx:xx:xx:xx, vifname=host1, bridge=bridge22' ]
disk = [ 'phy:/dev/mapper/xen_virtual_volume-host1_root,sda1,w',
         'phy:/dev/mapper/xen_virtual_volume-host1_var,sda2,w',
         'phy:/dev/mapper/xen_virtual_volume-host1_swap,sda3,w',
         'phy:/dev/mapper/xen_virtual_volume-host1_srv,sda4,w' ]
root = "/dev/sda1 ro"
extra = "4"

*Versions:*

app-emulation/xen-3.3.0
app-emulation/xen-tools-3.3.0
sys-kernel/xen-sources-2.6.21

Best regards,
Marcus

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