AVX CPU instruction support

[Luke Sudbery]

Hello,

 

Appologies for cross posting - I've posted here: http://discussions.citrix.com/topic/356958-avx-processor-instruction-support/ but got little response other than from a citrix employee saying to post here as well. So:

 

 

 

I'm trying to run code which has been compiled for AVX instructions, but this cpu capability isn't visible to my Xen guest or the host itself. How can I enable AVX on Xenserver?

 

Specially, the code in question is the 'Generic Mapping Tools': http://gmt.soest.hawaii.edu/

 

This simple test code: https://gist.github.com/mikesart/6832418 works fine when compiled and run on a physical box, but fails with 'illegal instruction' under XenServer:

[ccaalrs@aristotle00 bin]$ ./sse
Illegal instruction (core dumped)
[ccaalrs@aristotle00 bin]$

 

The servers are Dell R520, running the 6.2 with all the patest updates. They have 2x Xeon E5-2440, which should support AVX:

http://ark.intel.com...0-GTs-Intel-QPI

 

This is the output of host-cpu-info:

[root@xen05 ~]# xe host-cpu-info
cpu_count                : 24
             socket_count: 2
                   vendor: GenuineIntel
                    speed: 2400.052
                modelname: Intel® Xeon® CPU E5-2440 0 @ 2.40GHz
                   family: 6
                    model: 45
                 stepping: 7
                    flags: fpu de tsc msr pae mce cx8 apic sep mtrr mca cmov pat clflush acpi mmx fxsr sse sse2 ss ht nx constant_tsc nonstop_tsc aperfmperf pni pclmulqdq vmx est ssse3 sse4_1 sse4_2 x2apic popcnt aes hypervisor ida arat tpr_shadow vnmi flexpriority ept vpid
                 features: 17bee3ff-bfebfbff-00000001-2c100800
    features_after_reboot: 17bee3ff-bfebfbff-00000001-2c100800
        physical_features: 17bee3ff-bfebfbff-00000001-2c100800
                 maskable: full

 

/proc/cpuinfo from the host:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 45
model name      : Intel® Xeon® CPU E5-2440 0 @ 2.40GHz
stepping        : 7
cpu MHz         : 2400.052
cache size      : 15360 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
apicid          : 0
initial apicid  : 0
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu de tsc msr pae mce cx8 apic sep mtrr mca cmov pat clflush acpi mmx fxsr sse sse2 ss ht nx constant_tsc nonstop_tsc aperfmperf pni pclmulqdq vmx est ssse3 sse4_1 sse4_2 x2apic popcnt aes hypervisor ida arat tpr_shadow vnmi flexpriority ept vpid
bogomips        : 4825.77
clflush size    : 64
cache_alignment : 64
address sizes   : 46 bits physical, 48 bits virtual
power management:

 

 

/proc/cpuinfo from the guest:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 45
model name      : Intel® Xeon® CPU E5-2440 0 @ 2.40GHz
stepping        : 7
cpu MHz         : 2400.018
cache size      : 15360 KB
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat clflush mmx fxsr sse sse2 syscall nx lm rep_good unfair_spinlock pni pclmulqdq ssse3 cx16 sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes hypervisor lahf_lm
bogomips        : 4800.03
clflush size    : 64
cache_alignment : 64
address sizes   : 46 bits physical, 48 bits virtual
power management:

 

 

And /proc/cpuinfo from the same physical server booted with a live CD - confirming AVX is available on this server:

processor       : 23
vendor_id       : GenuineIntel
cpu family      : 6
model           : 45
model name      : Intel® Xeon® CPU E5-2440 0 @ 2.40GHz
stepping        : 7
microcode       : 0x70d
cpu MHz         : 2400.083
cache size      : 15360 KB
physical id     : 1
siblings        : 12
core id         : 5
cpu cores       : 6
apicid          : 43
initial apicid  : 43
fpu             : yes
fpu_exception   : yes
cpuid level     : 13
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 pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips        : 4804.57
clflush size    : 64
cache_alignment : 64
address sizes   : 46 bits physical, 48 bits virtual
power management:

 

 

I have seen other reports show avx available in host-cpu-info (eg here: http://discussions.c...ools-xenserver/). How can I enable AVX on Xenserver? Please let me know if you need any more info.

 

[shelley zhang]

I have the same problem. is there anyboby know how to fix this? :(

[Jiri Cerny]

Hello guys,

you need at least XS 6.5SP1 or 7.0.

 

See: https://bugs.xenserver.org/browse/XSO-460

 

Jiri

[Juraj Benadik]

I do have 6.5SP1 but still problem with AVX

In CentOS 7 guess I am unable to compile PHP 7.3

Does it have to be specifically enabled somehow?

[NIELS HANSSEN]

I'm having the same issues.. even on 7.6 HF 3
Skylake (HP DL380 Gen10).