[mvapich-discuss] apparent error

[Mark Potts]

Abhinav,
    You may be right, but I can not see how rigorous analysis
    could reveal the value for the default case for VBUF_TOTAL_SIZE
    should not be the same as that for either _SMALL_, _MEDIUM_, or
    _LARGE_CLUSTER.  In all other system types, you chose a value
    that was the same as _SMALL_CLUSTER as the default value.  EM64T
    (at line 51) seems to be the odd man out.
          regards,

Abhinav Vishnu wrote:
> Hi Mark,
> 
> Thanks for your mail. 
> 
>> Hi,
>>    I've noticed that in the MVAPICH 0.9.9 package included with OFED 1.2
>>    the source file mpid/ch_gen2_multirail/vbuf.h contains the following
>>    at line 51:
>>       #define VBUF_TOTAL_SIZE   (1024*16)
>>    However, all the similar code examples in this and related files
>>    indicates the intention was to assume _SMALL_CLUSTER when the cluster
>>    size is not specified.  Thus, I believe line 51 should be:
>>       #define VBUF_TOTAL_SIZE   (1024*12)
>>
>>    I have _not_ encountered a problem as a result of this apparent
>>    error, but it seems worthy of correcting.
> 
> We chose this value after rigorous analysis of performance with
> multi-rail device on our clusters. As you have mentioned, this
> is definitely not a problem. Please let us know if you have some
> data, which shows otherwise. We will be happy to take a look at it.
> 
> Thanks and best regards,
> 
> :- Abhinav
> 
>>         regards,
>> -- 
>> ***********************************
>>>> Mark J. Potts, PhD
>>>>
>>>> HPC Applications Inc.
>>>> phone: 410-992-8360 Bus
>>>>        410-313-9318 Home
>>>>        443-418-4375 Cell
>>>> email: potts at hpcapplications.com
>>>>        potts at excray.com
>> ***********************************
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-- 
***********************************
 >> Mark J. Potts, PhD
 >>
 >> HPC Applications Inc.
 >> phone: 410-992-8360 Bus
 >>        410-313-9318 Home
 >>        443-418-4375 Cell
 >> email: potts at hpcapplications.com
 >>        potts at excray.com
***********************************