[mpich-discuss] executing time

[bob ilgner]

hi, late at night here and forgot to include my timings also done on a 2
core PC:

1 Node(-n 1 i.e no comms)
Master wall clock time 0.074823

2 Node(-n 2)
Master wall clock time 0.041086

4 Node(-n 4)
Master Wall clock time 0.047954

8 Node(-n 8)
Master Wall clock time 0.062776

Which is what I would expect from a 2 core machine. I imagine that there is
an increase for n>2 as we have additional comms overhead.



regards, bob

On Tue, Jul 14, 2009 at 5:25 PM, bob ilgner <bobilgner at gmail.com> wrote:

> Hi WL,
>
> Had a quick look at the code and note that you can NOT run this as a serial
> process, i.e. using only 1 node. You will need to change code for that. -n 1
> does not run anything.
>
> I've added a few printf comments and wall clock timings to show when the
> code is running, and not running, i.e. with -n 1 it does not run. Try it out
> with these markers and see how it works out.
>
> Regards, bob
>
>
>
>
> On Tue, Jul 14, 2009 at 4:00 PM, samantha lin <wl8150 at googlemail.com>wrote:
>
>> Hi Bob,
>>
>> Yes, that was the command I executed. Apart from '2' processes, I also
>> tried a variety of numbers
>> and found '-n 1' is the fastest. I also made another similar C program
>> without using the MPI libraries.
>> The result was faster than '-n 1'. I didn't put a timing marks in the
>> program; instead, I use 'time' command
>> prefixing the executing command, e.g. "time mpiexec -n 2 myprog". (should
>> be okay?)
>> I added my program to this email. Hope that helps.
>>
>> Regards,
>> WL
>>
>> On Tue, Jul 14, 2009 at 2:25 PM, bob ilgner <bobilgner at gmail.com> wrote:
>>
>>> Hi WL,
>>>
>>> What mpiexec command are you using to run your program ? i.e. "mpiexec -n
>>> 2 xprogy"
>>> where xprogy is the name of your program ?
>>>
>>> What is your timing for the serial case and the timing for the multiple
>>> core case ? Is it a short program that you can list here so we can have a
>>> look at it ? Have you tried to place timing marks in the program to analyse
>>> what is happening ?
>>>
>>> Regards, bob
>>>
>>>
>>> On Tue, Jul 14, 2009 at 1:42 PM, samantha lin <wl8150 at googlemail.com>wrote:
>>>
>>>> Hi bob,
>>>>
>>>> It's running on a macbook pro(intel cpu 2 cores); just one laptop and
>>>> filesystem
>>>> is local.
>>>>
>>>> Regards,
>>>> WL
>>>> On Tue, Jul 14, 2009 at 5:37 AM, bob ilgner <bobilgner at gmail.com>wrote:
>>>>
>>>>> Hi WL,
>>>>>
>>>>> What hardware are you running the mpiexec on and what sort of process
>>>>> is this ? A little description please.
>>>>>
>>>>> Regards, bob
>>>>>
>>>>> On Tue, Jul 14, 2009 at 12:49 AM, samantha lin <wl8150 at googlemail.com>wrote:
>>>>>
>>>>>> Hi there,
>>>>>> I am new to MPICH. I just finished a test program which does
>>>>>> matrix multiplication. When I used 'mpiexec' to execute the
>>>>>> program, I found that the more processes, the longer it takes.
>>>>>> Not sure if the result is correct or not? Or I should do some
>>>>>> things more to improve it?
>>>>>>
>>>>>> WL
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
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