Re: [eigen] cache queries bug?

[Gael Guennebaud <gael.guennebaud@xxxxxxxxx>]

should be fine now.

gael

On Sun, Jun 27, 2010 at 12:03 AM, Ben Goodrich <bgokgm@xxxxxxxxxxxxxx> wrote:
> Hi,
>
> On Sat, Jun 26, 2010 at 5:19 PM, Gael Guennebaud
> <gael.guennebaud@xxxxxxxxx> wrote:
>> hi,
>>
>> I've just added a small utility to help debugging this. So could you
>> please update your local copy, and send me back the output of the
>> following commands:
>>
>> $ cd path_to_eigen/bench
>> $ g++ check_cache_queries.cpp -I .. && ./a.out
>
> I get no output in over 3 minutes of CPU time. On the core duo it
> spits out all the info almost instantly, but I imagine you already
> know what that says.
>
>> Also could you retry ./check cholesky ? I've also committed a small
>> fix which could partially solve the issue.
>
> Still hanging on cholesky_2.
>
> Ben
>
>> On Sat, Jun 26, 2010 at 8:40 PM, Ben Goodrich <bgokgm@xxxxxxxxxxxxxx> wrote:
>>> Hi,
>>>
>>> If you want to postpone this until after the beta is released, that is fine.
>>>
>>> I have two machines, both with the "same" software (disregarding the
>>> bitness difference) with Debian unstable and g++ 4.4.4.
>>>
>>> One is a core duo desktop from a couple of years ago
>>>
>>> bgoodrich@Room320:/tmp/eigen/test$ cat /proc/cpuinfo
>>> processor       : 0
>>> vendor_id       : GenuineIntel
>>> cpu family      : 6
>>> model           : 15
>>> model name      : Intel(R) Core(TM)2 CPU          6300  @ 1.86GHz
>>> stepping        : 6
>>> cpu MHz         : 600.000
>>> cache size      : 2048 KB
>>> physical id     : 0
>>> siblings        : 2
>>> core id         : 0
>>> cpu cores       : 2
>>> apicid          : 0
>>> initial apicid  : 0
>>> fpu             : yes
>>> fpu_exception   : yes
>>> cpuid level     : 10
>>> 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 lm constant_tsc arch_perfmon pebs bts rep_good aperfmperf
>>> pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm
>>> tpr_shadow
>>> bogomips        : 3721.67
>>> 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           : 15
>>> model name      : Intel(R) Core(TM)2 CPU          6300  @ 1.86GHz
>>> stepping        : 6
>>> cpu MHz         : 600.000
>>> cache size      : 2048 KB
>>> physical id     : 0
>>> siblings        : 2
>>> core id         : 1
>>> cpu cores       : 2
>>> apicid          : 1
>>> initial apicid  : 1
>>> fpu             : yes
>>> fpu_exception   : yes
>>> cpuid level     : 10
>>> 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 lm constant_tsc arch_perfmon pebs bts rep_good aperfmperf
>>> pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm
>>> tpr_shadow
>>> bogomips        : 3720.69
>>> clflush size    : 64
>>> cache_alignment : 64
>>> address sizes   : 36 bits physical, 48 bits virtual
>>> power management:
>>>
>>> and one is a really old laptop (don't laugh)
>>>
>>> goodrich@X41Laptop:/tmp/eigen$ cat /proc/cpuinfo
>>> processor       : 0
>>> vendor_id       : GenuineIntel
>>> cpu family      : 6
>>> model           : 13
>>> model name      : Intel(R) Pentium(R) M processor 1.50GHz
>>> stepping        : 8
>>> cpu MHz         : 600.000
>>> cache size      : 2048 KB
>>> fdiv_bug        : no
>>> hlt_bug         : no
>>> f00f_bug        : no
>>> coma_bug        : no
>>> fpu             : yes
>>> fpu_exception   : yes
>>> cpuid level     : 2
>>> wp              : yes
>>> flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
>>> mca cmov clflush dts acpi mmx fxsr sse sse2 ss tm pbe nx up bts est
>>> tm2
>>> bogomips        : 1196.71
>>> clflush size    : 64
>>> cache_alignment : 64
>>> address sizes   : 32 bits physical, 32 bits virtual
>>> power management:
>>>
>>> On the 32 bit laptop, I have encountered a problem where things like
>>>
>>> ./check.sh cholesky
>>>
>>> hang for minutes before I kill them, while on the 64 bit core duo
>>> desktop, this finishes in a few seconds.
>>>
>>> I bisected the problem to
>>>
>>> goodrich@X41Laptop:/tmp/eigen$ hg bisect --bad
>>> The first bad revision is:
>>> changeset:   3027:c93abfa8ffcb
>>> parent:      3023:c3b8e6edde53
>>> user:        Gael Guennebaud <g.gael@xxxxxxx>
>>> date:        Wed Jun 23 16:34:51 2010 +0200
>>> summary:     fix cache queries for non core2 CPU ;)
>>>
>>> But I don't know what to do from here because I don't really
>>> understand low-level issues like this.
>>>
>>> Thank you,
>>> Ben
>>>
>>>
>>>
>>
>>
>>
>
>
>