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Re: [GridSim-users] Question regarding simulation time
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From:
<ag...@ds...> - 2008-01-08 08:38:55
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Hello everybody,
I've tryed to find an answer for this query, but I can't.
So, can any of you try to help Chainan with this?
Thanks, and Happy 2008,
Agustin
Chainan Satayapiwat escribió:
> Good morning Agustin,
>
> First, thank you very much for your prompt reply. I think I'm understand
> about start time of the job now but I am still in doubt about the reason
> makes the lower bandwidth user having its gridlet ready for execution
> earlier than higher bandwidth. I am sorry that I think I was not able to
> explain my questions clearly last time. Let me try to put those
> questions again. I will put the program code and result here for ease of
> discussion.
>
> ----QUOTE (TestCase1.java)----
>
> // sends all the Gridlets
> Gridlet gl = null;
> boolean success;
> for (i = 0; i < list_.size(); i++)
> {
> gl = (Gridlet) list_.get(i);
>
> // For even number of Gridlets, send with an acknowledgement
> if (i % 2 == 0)
> {
> success = super.gridletSubmit(gl,
> resourceID[index],0.0,true);
> System.out.println(name_ + ": Sending Gridlet #" +
> gl.getGridletID() + " with status = " + success +
> " to " + resourceName[index]);
> }
>
> // For odd number of Gridlets, send without an
> acknowledgement
> else
> {
> success = super.gridletSubmit(gl, resourceID[index],
> 0.0,false);
> System.out.println(name_ + ": Sending Gridlet #" +
> gl.getGridletID() + " with NO ACK so status = " +
> success + " to " + resourceName[index]);
> }
> }
>
> ----End of QUOTE----
>
> >From the code above, will each user submit all gridlet to
> resourceID[index] at the same time? Let's say 4 gridlet per user in this
> example, should they all send to execute at the same time? Or the
> submission of job is hold until the termination of earlier gridlet?
>
> My understanding is if it is even (ack is required), then, the
> submission of next gridlet is hold until the first gridlet already
> submitted (it probably haven't started its execution yet but the job is
> already transferred along with its in_file.) Otherwise (no ack), the
> next gridlet is submitted immediately (the gridlet may not yet finish
> transferring the in_file while new gridlet is submitted) Am I correctly
> understood?
>
> If so, the users bandwidth should have an impact on the start time (I
> mean the time that user starts to submit the gridlet, not the starts of
> execution of gridlet) and duration of the gridlet's submission. Lower
> bandwidth leads to longer time to make the gridlet into the "ready for
> execution" state, and also delay in submission of subsequent gridlet (to
> be more specific, gridletSubmit causes longer delay, if it requires ack)
>
> Now, let's back to Gridlet's result. I copied only first Gridlet of both
> user here. Please notice the line with **** is highlight the submission
> time.
>
> ------QUOTE - User0 - Gridlet 1 result -------
>
> Time (sec) Description Gridlet #0
> ------------------------------------------
> 0.00 Creates Gridlet ID #0
> 0.00 Assigns the Gridlet to User_0 (ID #17)
> 11.00 Allocates this Gridlet to GridResource_0 (ID #5) with cost =
> $3.0/sec
> 11.00 Sets the submission time to 11.00 ****
> 11.00 Sets Gridlet status from Created to InExec
> 11.00 Sets the execution start time to 11.00
> 112.00 Sets Gridlet status from InExec to Success
> 112.00 Sets the wall clock time to 101.00 and the actual CPU time to
> 101.00
> 112.00 Sets the length's finished so far to 1000.0
>
> Gridlet #0, length = 1000.0, finished so far = 1000.0
> ===========================================
>
> -------End of QUOTE----------------------
>
> ------QUOTE - User1 - Gridlet 1 result -------
>
> Time (sec) Description Gridlet #0
> ------------------------------------------
> 0.00 Creates Gridlet ID #0
> 0.00 Assigns the Gridlet to User_1 (ID #20)
> 19.00 Allocates this Gridlet to GridResource_0 (ID #5) with cost =
> $3.0/sec
> 19.00 Sets the submission time to 19.00 ****
> 19.00 Sets Gridlet status from Created to InExec
> 19.00 Sets the execution start time to 19.00
> 120.00 Sets Gridlet status from InExec to Success
> 120.00 Sets the wall clock time to 101.00 and the actual CPU time to
> 101.00
> 120.00 Sets the length's finished so far to 1000.0
>
> Gridlet #0, length = 1000.0, finished so far = 1000.0
> ===========================================
>
> -------End of QUOTE----------------------
>
> Because, for these 2 gridlets, both are start immediately once the it is
> ready for execution. So, now, let's put topic of the execution time off
> for a second. From the line with highlight, I doubt that even User1 has
> 5x higher bandwidth. Why it is slower (ready at 19th sec while 11th sec
> for User0)? And if you see from my previous email, this happens for
> every pairs of gridlet. So, what is the factor that make it "ready for
> submission to PE" later than User0?
>
> Sorry for very long email. I think it starts to sound complicate to me.
> Please kindly let me know, if further information is needed. Thank you
> for your valuable time in helping this.
>
> Best Regards,
> Chainan Satayapiwat
> Research Student, Tohoku University
>
>
> On Thu, 2007-12-27 at 10:11 +0100, Agustín Caminero Herráez wrote:
>
>> Hi Chainan,
>>
>> I think I can give some hints to fix your problem.
>>
>> First, you say that "- Gridlet#0 size 1000 submitted at 11.00 starts at
>> 11.00 ". This means, to my understanding, that the gridlet is being
>> submitted at time 11.00 and its execution starts at 11.00. This means
>> that the second 11.00 includes the network transmission time + the time
>> to wait for a idle PE at the resource. Since this is the first gridlet,
>> all PEs are idle so it starts being executed straight-away.
>> If u pay attention, the start time is the same as the submission time
>> for the first 3 gridlets in your sims, because your resource has 3 PEs.
>> Delays begin when all the PEs are busy, so they are created because of
>> congestion at the resource.
>>
>> In order to test the network performance, you can create a bigger
>> resource (with more PEs) so that time differences between gridlets will
>> be caused by the network transmission, not by contention at the
>> resource. If there are no differences, try making the gridlets IO files
>> bigger.
>>
>> Hope this is useful.
>>
>> All the best,
>>
>> Agustin
>>
>> Chainan Satayapiwat escribio':
>>
>>> Hi,
>>>
>>> I was studying the sample code which provided in
>>> http://www.gridbus.org/gridsim/example/index.html Specifically, my
>>> problem was coming from the example 7 (Test.java & TestCase1.java) when
>>> running the simulation. The allocation policy was space sharing.
>>>
>>> There are 2 users (User_0 and User_1) I saw all the Gridlet from User_0
>>> start queuing for processing earlier than User_1 but the lenght of
>>> Gridlet (which seems to use as Gridlet size, in_file size, and out_file
>>> size) are all the same. Given the User_1 has 5 times higher bandwidth,
>>> then, I would assume that the User_1 start time should be earlier than
>>> User_0. However, here are the result of simulation
>>>
>>> Here are the detail.
>>> All Gridlet schedules onto 1 Machine with 3 PEs.
>>> User_0 (Bandwidth 1000) has
>>> - Gridlet#0 size 1000 submitted at 11.00 starts at 11.00
>>> - Gridlet#1 size 2000 submitted at 35.00 starts at 35.00
>>> - Gridlet#2 size 3000 submitted at 75.00 starts at 120.00
>>> - Gridlet#3 size 4000 submitted at 131.00 starts at 313.00
>>>
>>> User_1 (Bandwidth 5000) has
>>> - Gridlet#0 size 1000 submitted at 19.00 starts at 19.00
>>> - Gridlet#1 size 2000 submitted at 51.00 starts at 112.00
>>> - Gridlet#2 size 3000 submitted at 99.00 starts at 236.00
>>> - Gridlet#3 size 4000 submitted at 163.00 starts at 421.00
>>>
>>> As shown above, I can't understand how it works here. User with higher
>>> bandwidth should be able to finish uploading the file to the processing
>>> machine first and, thus, the job should be ready to submit earlier.
>>> Therefore, I tried to make sure if this is about bandwidth things by
>>> hardcode in the TestCase1.java in createGridlet method by fixing the
>>> size of input file. (i.e. third parameter of Gridlet constructor) As
>>> expected, all Gridlet starts at 3rd second of simulation time. (This is
>>> considered immediate as the code wait 3 units of time in the beginning)
>>> So, I'm quite sure that the delay is coming from the simulation of file
>>> transfer that required before the program execution. So, why the higher
>>> bandwidth is slower? Perhaps, I misunderstood at some points and confuse
>>> myself. Could anyone kindly help me out on this?
>>>
>>> Thank you.
>>>
>>> Best Regards,
>>> Chainan Satayapiwat
>>> Research Student, Tohoku University
>>>
>>>
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>>>
>
>
--
========================================================
Agustin Caminero
PhD Student
Computing Systems Department
The University of Castilla La Mancha, Albacete. Spain.
Phone: +34 967 599 200 Ext. 2693. Fax: +34 967 599 343
http://www.i3a.uclm.es/
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