Test/build failure (Illegal instruction)

[pao]

v0.2.2. Log (from within a Julia build): http://http://sprunge.us/ADMc

Ubuntu 11.10 VM in VirtualBox, with access to four logical cores.

/proc/cpuinfo:

processor   : 0
vendor_id   : GenuineIntel
cpu family  : 6
model       : 42
model name  : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping    : 7
cpu MHz     : 2170.020
cache size  : 6144 KB
physical id : 0
siblings    : 4
core id     : 0
cpu cores   : 4
apicid      : 0
initial apicid  : 0
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc rep_good nopl pni ssse3 lahf_lm
bogomips    : 4340.04
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor   : 1
vendor_id   : GenuineIntel
cpu family  : 6
model       : 42
model name  : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping    : 7
cpu MHz     : 2170.020
cache size  : 6144 KB
physical id : 0
siblings    : 4
core id     : 1
cpu cores   : 4
apicid      : 1
initial apicid  : 1
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc rep_good nopl pni ssse3 lahf_lm
bogomips    : 4381.94
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor   : 2
vendor_id   : GenuineIntel
cpu family  : 6
model       : 42
model name  : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping    : 7
cpu MHz     : 2170.020
cache size  : 6144 KB
physical id : 0
siblings    : 4
core id     : 2
cpu cores   : 4
apicid      : 2
initial apicid  : 2
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc rep_good nopl pni ssse3 lahf_lm
bogomips    : 4308.74
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor   : 3
vendor_id   : GenuineIntel
cpu family  : 6
model       : 42
model name  : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping    : 7
cpu MHz     : 2170.020
cache size  : 6144 KB
physical id : 0
siblings    : 4
core id     : 3
cpu cores   : 4
apicid      : 3
initial apicid  : 3
fpu     : yes
fpu_exception   : yes
cpuid level : 5
wp      : yes
flags       : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc rep_good nopl pni ssse3 lahf_lm
bogomips    : 4414.10
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

[xianyi]

Hi ,

VirtualBox didn't support AVX instruction.

Because OpenBLAS detects your VM as Sandy Bridge, it uses AVX kernels.
Thus, it causes
the illegal instruction fault.

You can "make TARGET=NEHALEM".

Thanks

Xianyi

2012/7/9 pao <
[email protected]

v0.2.2. Log (from within a Julia build): http://http://sprunge.us/ADMc

Ubuntu 11.10 VM in VirtualBox, with access to four logical cores.

/proc/cpuinfo:

processor       : 0
vendor_id       : GenuineIntel
cpu family      : 6
model           : 42
model name      : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping        : 7
cpu MHz         : 2170.020
cache size      : 6144 KB
physical id     : 0
siblings        : 4
core id         : 0
cpu cores       : 4
apicid          : 0
initial apicid  : 0
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc
rep_good nopl pni ssse3 lahf_lm
bogomips        : 4340.04
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor       : 1
vendor_id       : GenuineIntel
cpu family      : 6
model           : 42
model name      : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping        : 7
cpu MHz         : 2170.020
cache size      : 6144 KB
physical id     : 0
siblings        : 4
core id         : 1
cpu cores       : 4
apicid          : 1
initial apicid  : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc
rep_good nopl pni ssse3 lahf_lm
bogomips        : 4381.94
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor       : 2
vendor_id       : GenuineIntel
cpu family      : 6
model           : 42
model name      : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping        : 7
cpu MHz         : 2170.020
cache size      : 6144 KB
physical id     : 0
siblings        : 4
core id         : 2
cpu cores       : 4
apicid          : 2
initial apicid  : 2
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc
rep_good nopl pni ssse3 lahf_lm
bogomips        : 4308.74
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

processor       : 3
vendor_id       : GenuineIntel
cpu family      : 6
model           : 42
model name      : Intel(R) Core(TM) i7-2720QM CPU @ 2.20GHz
stepping        : 7
cpu MHz         : 2170.020
cache size      : 6144 KB
physical id     : 0
siblings        : 4
core id         : 3
cpu cores       : 4
apicid          : 3
initial apicid  : 3
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx lm constant_tsc
rep_good nopl pni ssse3 lahf_lm
bogomips        : 4414.10
clflush size    : 64
cache_alignment : 64
address sizes   : 36 bits physical, 48 bits virtual
power management:

---

Reply to this email directly or view it on GitHub:
#124

[pao]

Ah, that explains why this just recently broke. Thanks! I'll try to verify this soon, and leave it up to you to decide how you want to resolve.

[xianyi]

Hi pao,

I think this is Virtual Box issue. It should support AVX.

To my knowledge, KVM supports AVX. I use a Sandy Bridge Win7 64-bit KVM machine to test OpenBLAS.

Xianyi

[Keno]

VMWare supports AVX as well.

[pao]

Agree that it is a VBox issue; just leaving it up to you to decide whether it's worth handling as a special case or not, rather than closing the issue out from under you. I'm not concerned with the performance loss since I'm just using it for Julia development; switching to VMWare is really more trouble than it's worth to me. Thanks for the pointer, though.

[zchothia]

It isn't actually too difficult to detect whether AVX is actually supported by the operating system/virtualization software. For reference here is small program based on code from one of Agner Fog's libraries: https://gist.github.com/3078968.

I have limited time at the moment, but it would certainly be welcomed if this was incorporated into OpenBLAS's detection routines.

--Zaheer

[pao]

Can confirm that setting TARGET=NEHALEM works fine. Thanks!

[xianyi]

Hi @pao ,

Could you try OpenBLAS develop branch.
It detects OS supporting AVX on runtime. If not, it will use old Nehalem kernels.

Thank you

Xianyi

[pao]

Yes, I just built it and it correctly selected the Nehalem kernels. Thanks!

[staticfloat]

@xianyi, I have discovered the problem that OpenBLAS faces with some virtualization suites. It seems that the way e.g. Amazon EC2 nodes "disable" AVX is to disable XSAVE instead, as if XSAVE is disabled, AVX is also not available. Is it possible to check for XSAVE as well when checking to see if AVX is available?

[xianyi]

@staticfloat , Thank you for the tip. I will implement it in develop branch.