Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |  

This web mail archive is frozen.

This page is part of a frozen web archive of this mailing list.

You can still navigate around this archive, but know that no new mails have been added to it since July of 2016.

Click here to be taken to the new web archives of this list; it includes all the mails that are in this frozen archive plus all new mails that have been sent to the list since it was migrated to the new archives.

Subject: Re: [OMPI users] Binding to Core Warning
From: Saliya Ekanayake (esaliya_at_[hidden])
Date: 2014-02-26 15:17:48


I have a followup question on this. In our application we have parallel for
loops similar to OMP parallel for. I noticed that in order to gain speedup
with threads I've to set --bind-to none, otherwise multiple threads will
bind to same core giving no increase in performance. For example, I get
following (attached) performance for a simple 3point stencil computation
run with T threads on 1 MPI process on 1 node (Tx1x1).

My understanding is even when there are multiple procs per node we should
use --bind-to none in order to get performance with threads. Is this
correct? Also, what's the disadvantage of not using --bind-to core?

Thank you,
Saliya

On Wed, Feb 26, 2014 at 11:01 AM, Saliya Ekanayake <esaliya_at_[hidden]>wrote:

> Thank you Ralph, I'll check this.
>
>
> On Wed, Feb 26, 2014 at 10:04 AM, Ralph Castain <rhc_at_[hidden]> wrote:
>
>> It means that OMPI didn't get built against libnuma, and so we can't
>> ensure that memory is being bound local to the proc binding. Check to see
>> if numactl and numactl-devel are installed, or you can turn off the warning
>> using "-mca hwloc_base_mem_bind_failure_action silent"
>>
>>
>> On Feb 25, 2014, at 10:32 PM, Saliya Ekanayake <esaliya_at_[hidden]> wrote:
>>
>> Hi,
>>
>> I tried to run an MPI Java program with --bind-to core. I receive the
>> following warning and wonder how to fix this.
>>
>>
>> WARNING: a request was made to bind a process. While the system
>> supports binding the process itself, at least one node does NOT
>> support binding memory to the process location.
>>
>> Node: 192.168.0.19
>>
>> This is a warning only; your job will continue, though performance may
>> be degraded.
>>
>>
>> Thank you,
>> Saliya
>>
>> --
>> Saliya Ekanayake esaliya_at_[hidden]
>> Cell 812-391-4914 Home 812-961-6383
>> http://saliya.org
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>>
>>
>> _______________________________________________
>> users mailing list
>> users_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/users
>>
>
>
>
> --
> Saliya Ekanayake esaliya_at_[hidden]
> Cell 812-391-4914 Home 812-961-6383
> http://saliya.org
>

-- 
Saliya Ekanayake esaliya_at_[hidden]
Cell 812-391-4914 Home 812-961-6383
http://saliya.org



3pointstencil.png