True. I was curious as to what happens when I am time sharing the CPU.
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On May 8, 2012, at 3:11 AM, TERRY DONTJE wrote:
> On 5/7/2012 8:40 PM, Jeff Squyres (jsquyres) wrote:
>>
>> On May 7, 2012, at 8:31 PM, Jingcha Joba wrote:
>>
>>> So in the above stated example, end-
On 5/7/2012 8:40 PM, Jeff Squyres (jsquyres) wrote:
On May 7, 2012, at 8:31 PM, Jingcha Joba wrote:
So in the above stated example, end-start will be: +
20ms ?
(time slice of P2 + P3 = 20ms)
More or less (there's nonzero amount of time required for the kernel scheduler,
and the time quantu
On May 7, 2012, at 8:31 PM, Jingcha Joba wrote:
> So in the above stated example, end-start will be:
> + 20ms ?
>
> (time slice of P2 + P3 = 20ms)
More or less (there's nonzero amount of time required for the kernel scheduler,
and the time quantum for each of P2 and P3 is likely not *exactly
Jeff,
So in the above stated example, end-start will be: + 20ms ?
(time slice of P2 + P3 = 20ms)
On Mon, May 7, 2012 at 1:42 PM, Jeff Squyres (jsquyres)
wrote:
> On May 7, 2012, at 2:39 PM, Jingcha Joba wrote:
>
> > OK.This explains that if a process gets "migrated" from one CPU to
> another,
On May 7, 2012, at 2:39 PM, Jingcha Joba wrote:
> OK.This explains that if a process gets "migrated" from one CPU to another,
> the time is not "affected". But it still doesn't explain if the process gets
> scheduled back to the same CPU.
MPI_Wtime() doesn't tell you any of this stuff. It just
OK.This explains that if a process gets "migrated" from one CPU to another,
the time is not "affected". But it still doesn't explain if the process
gets scheduled back to the same CPU.
Just in case I have not explained my question clearly, let me explain it
from the schedular's perspective.
Lets a
MPI_Wtime() returns the elapsed time since some arbitrary time in the
past. It is a measure of "wallclock" time, not of CPU time or anything.
On 5/4/2012 3:08 PM, Jingcha Joba wrote:
Lets say I have a code like this
start = MPI_Wtime()
stop = MPI_Wtime();
What happens when right after start=M
Lets say I have a code like this
start = MPI_Wtime()
stop = MPI_Wtime();
What happens when right after start=MPI_Wtime(), the timeslice of the
process ( from the operating system's perspective not the MPI process) is
over, and the operating system schedules a next process, after saving the
conte
A few nodes:
1. I think you posted an incorrect version of your code -- it's calling
MPI_Test on an uninitialized request.
2. This looks like a homework problem. I try very hard not to do peoples'
homework. :-) My first comment to you stands: you need to be more
fine-grained in your timing
Hi,
I haven't used the more mpi process also but still am still unable to
reduce my exection time.Here is my code *http://seshendramln.blogspot.se/*
and please help me in solving.
In this code iam getting the same execution time in i increase or decrease
the no.of nodes.
thanking you
With regard
You probably need to be more fine-grained in your timing. Find out exactly
what is increasing in time. This is a common symptom for codes that do not
scale well -- i.e., adding more MPI processes actually causes it to slow down.
On May 3, 2012, at 7:48 AM, seshendra seshu wrote:
> Hi,
> I ha
On May 3, 2012, at 2:02 PM, Jingcha Joba wrote:
> Not related to this question , but just curious, is Wtime context switch safe
> ?
Not sure exactly what you're asking here...?
--
Jeff Squyres
jsquy...@cisco.com
For corporate legal information go to:
http://www.cisco.com/web/about/doing_busin
Not related to this question , but just curious, is Wtime context switch safe ?
--
Sent from my iPhone
On May 3, 2012, at 4:48 AM, seshendra seshu wrote:
> Hi,
> I have written an parallel program and when i run my program on 4,8,16 nodes
> and calculated the execution time at master using MPI
Hi, could you also attach your current code ?
Regards
Björn
From: users-boun...@open-mpi.org [mailto:users-boun...@open-mpi.org] On
Behalf Of seshendra seshu
Sent: den 3 maj 2012 13:49
To: Open MPI Users
Subject: [OMPI users] Regarding the execution time calculation
Hi,
I have written
Hi,
I have written an parallel program and when i run my program on 4,8,16
nodes and calculated the execution time at master using MPI_Wtime in master
node. The problem the execution time is increasing rapidly like NON
parallel program-55 sec, and for parallel program 2-nodes--60sec , 4-nodes
74sec
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