[gmx-users] GPU ECC question

[Szilárd Páll]

On Sat, Jun 8, 2013 at 9:21 PM, Albert <mailmd2011 at gmail.com> wrote:
> Hello:
>
>  Recently I found a strange question about Gromacs-4.6.2 on GPU workstaion.
> In my GTX690 machine, when I run md production I found that the ECC is on.
> However, in my another GTX590 machine, I found the ECC was off:
>
> 4 GPUs detected:
>   #0: NVIDIA GeForce GTX 590, compute cap.: 2.0, ECC:  no, stat: compatible
>   #1: NVIDIA GeForce GTX 590, compute cap.: 2.0, ECC:  no, stat: compatible
>   #2: NVIDIA GeForce GTX 590, compute cap.: 2.0, ECC:  no, stat: compatible
>   #3: NVIDIA GeForce GTX 590, compute cap.: 2.0, ECC:  no, stat: compatible
>
> moreover, there is only two GTX590 in the machine, I don't know why Gromacs
> claimed 4 GPU detected. However, in my another Linux machine which also have
> two GTX590, Gromacs-4.6.2 only find 2 GPU, and ECC is still off.
>
> I am just wondering:
>
> (1) why in GTX690 the ECC can be on while it is off in my GTX590? I compiled
> Gromacs with the same options and the same version of intel compiler

Unless your 690 is in fact a Tesla K10 it does surely not support ECC!
Note that ECC is not something I personally think you really need.

>
> (2) why in machines both of physically installed two GTX590 cards, one of
> them was detected with 4 GPU while the other was claimed contains two GPU?
>

Both GTX 590 and 690 are dual-chip boards which means two independent
processing units with their own memory mounted on the same card and
connected by a PCI switch (NVIDIA NF200). Hence, the two GPUs on these
dual-chip boards will be enumerated as a separate devices. You can
double-check this in nvidia-smi which should give the same devices as
what mdrun reports. I suspect that one of the GPUs which is shown to
have only two GPUs suffers from some hardware or software issues.


Regards,
Szilard

> thank you very much
>
> best
> Albert
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