en with "constant TSC" feature (which is no longer
> constant again).
> >
> > Kind regards,
> > Alex Granovsky
> >
> >
> >
> > -Original Message- From: Gilles Gouaillardet
> > Sent: Thursday, November 27, 2014 1:13 PM
> > T
ent: Thursday, November 27, 2014 1:13 PM
> To: Open MPI Users
> Subject: Re: [OMPI users] mpi_wtime implementation
>
> Folks,
>
> one drawback of retrieving time with rdtsc is that this value is core
> specific :
> if a task is not bound to a core, then the value returned b
sky
-Original Message-
From: Gilles Gouaillardet
Sent: Thursday, November 27, 2014 1:13 PM
To: Open MPI Users
Subject: Re: [OMPI users] mpi_wtime implementation
Folks,
one drawback of retrieving time with rdtsc is that this value is core
specific :
if a task is not bound to a core, then t
Folks,
one drawback of retrieving time with rdtsc is that this value is core
specific :
if a task is not bound to a core, then the value returned by MPI_Wtime()
might go backward.
if i run the following program with
taskset -c 1 ./time
and then move it accross between cores
(taskset -cp 0 ; tas
On Nov 24, 2014, at 12:06 AM, George Bosilca wrote:
> https://github.com/open-mpi/ompi/pull/285 is a potential answer. I would like
> to hear Dave Goodell comment on this before pushing it upstream.
>
> George.
I'll take a look at it today. My notification settings were messed up when you
https://github.com/open-mpi/ompi/pull/285 is a potential answer. I would
like to hear Dave Goodell comment on this before pushing it upstream.
George.
On Wed, Nov 19, 2014 at 12:56 PM, George Bosilca
wrote:
> Dave,
>
> You’re right, we screwed up (some #define not correctly set). I have a
>
Dave,
You’re right, we screwed up (some #define not correctly set). I have a patch,
I’ll push it asap.
George.
> On Nov 19, 2014, at 05:19 , Dave Love wrote:
>
> "Daniels, Marcus G" writes:
>
>> On Mon, 2014-11-17 at 17:31 +, Dave Love wrote:
>>> I discovered from looking at the mpiP
"Daniels, Marcus G" writes:
> On Mon, 2014-11-17 at 17:31 +, Dave Love wrote:
>> I discovered from looking at the mpiP profiler that OMPI always uses
>> gettimeofday rather than clock_gettime to implement mpi_wtime on
>> GNU/Linux, and that looks sub-optimal.
>
> It can be very expensive in
On Mon, 2014-11-17 at 17:31 +, Dave Love wrote:
> I discovered from looking at the mpiP profiler that OMPI always uses
> gettimeofday rather than clock_gettime to implement mpi_wtime on
> GNU/Linux, and that looks sub-optimal.
It can be very expensive in practice, especially for codes that ha
I discovered from looking at the mpiP profiler that OMPI always uses
gettimeofday rather than clock_gettime to implement mpi_wtime on
GNU/Linux, and that looks sub-optimal. I don't remember what the
resolution of gettimeofday is in practice, but I did need to write a
drop-in replacement for benchm
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