[gmx-users] Can we set the number of pure PME nodes when using GPU&CPU?

[Mark Abraham]

That's not what I said.... "You can set..."

-npme behaves the same whether or not GPUs are in use. Using separate ranks
for PME caters to trying to minimize the cost of the all-to-all
communication of the 3DFFT. That's still relevant when using GPUs, but if
separate PME ranks are used, any GPUs on nodes that only have PME ranks are
left idle. The most effective approach depends critically on the hardware
and simulation setup, and whether you pay money for your hardware.

Mark


On Sat, Aug 9, 2014 at 2:56 AM, Theodore Si <sjyzhxw at gmail.com> wrote:

> Hi,
>
> You mean no matter we use GPU acceleration or not, -npme is just a
> reference?
> Why we can't set that to a exact value?
>
>
> On 8/9/2014 5:14 AM, Mark Abraham wrote:
>
>> You can set the number of PME-only ranks with -npme. Whether it's useful
>> is
>> another matter :-) The CPU-based PME offload and the GPU-based PP offload
>> do not combine very well.
>>
>> Mark
>>
>>
>> On Fri, Aug 8, 2014 at 7:24 AM, Theodore Si <sjyzhxw at gmail.com> wrote:
>>
>>  Hi,
>>>
>>> Can we set the number manually with -npme when using GPU acceleration?
>>>
>>>
>>> --
>>> Gromacs Users mailing list
>>>
>>> * Please search the archive at http://www.gromacs.org/
>>> Support/Mailing_Lists/GMX-Users_List before posting!
>>>
>>> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
>>>
>>> * For (un)subscribe requests visit
>>> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
>>> send a mail to gmx-users-request at gromacs.org.
>>>
>>>
> --
> Gromacs Users mailing list
>
> * Please search the archive at http://www.gromacs.org/
> Support/Mailing_Lists/GMX-Users_List before posting!
>
> * Can't post? Read http://www.gromacs.org/Support/Mailing_Lists
>
> * For (un)subscribe requests visit
> https://maillist.sys.kth.se/mailman/listinfo/gromacs.org_gmx-users or
> send a mail to gmx-users-request at gromacs.org.
>