[gmx-users] GPU and aux power supply

Thu Jul 2 15:57:17 CEST 2015

I'm curious what are the conditions under which you get such a exceptional
speedup. Can you share your input files and/or log files?

--
Szilárd

On Thu, Jul 2, 2015 at 2:18 AM, Alex <nedomacho at gmail.com> wrote:

> Yup, about 7-8 times between with and without GPU acceleration, not making
> this up: I had 11 ns/day and now ~80-87 ns/day, the numbers vary a bit.
> I've been getting a similar boost on our GPU-accelerated cluster node (dual
> core i7, 8 cores each) with two Tesla C2075 cards (I am directing my
> simulations to one of them via -gpu_id).
> All runs are -ntomp 4, with or without GPU. The physics in all cases is
> perfectly acceptable. So far I only tested my new box on vacuum
> simulations, about to run the solvated version (~30K particles).
>
> Alex
>
>
> On Wed, Jul 1, 2015 at 6:09 PM, Szilárd Páll <pall.szilard at gmail.com>
> wrote:
>
>> Hmmm, 8x sounds rather high, are you sure you are comparing to CPU-only
>> runs that use proper SIMD optimized kernels?
>>
>> Because of the way offload-based acceleration works, the CPU and GPU will
>> inherently be executing concurrently only part of the runtime and as a
>> consequence the GPU is idle part of the run-time (during
>> integration+constraints). You can make use of this idle time by running
>> multiple independent simulations concurrently. This can yield serious
>> improvements in terms of _aggregate_ simulation performance especially with
>> small inputs and many cores (see slide 51 https://goo.gl/7DnSri)/
>>
>> --
>> Szilárd
>>
>> On Wed, Jul 1, 2015 at 4:16 AM, Alex <nedomacho at gmail.com> wrote:
>>
>>>  I am happy to say that I am getting an 8-fold increase in simulation
>>> speeds for $200.
>>>
>>>
>>> An additional question: normally, how many simulations (separate mdruns
>>> on separate CPU cores) can be performed simultaneously on a single GPU?
>>> Say, for 20-40K particle sized simulations.
>>>
>>> The coolers are not even spinning during a single test (mdrun -ntomp 4),
>>> and I get massive acceleration. They aren't broken, the card is just cool
>>> (small system, ~3K particles).
>>>
>>>
>>> Thanks,
>>>
>>>
>>> Alex
>>>
>>>
>>>
>>>   >
>>>
>>>
>>>
>>>
>>>   >
>>>
>>> Ah, ok, so you can get a 6-pin from the PSU and another from a converted
>>> molex connector. That should be just fine, especially as the card should
>>> will not pull more than ~155W (under heavy graphics load) based on the
>>> Tomshardware review* and you are providing 225W max.
>>>
>>>
>>>
>>> *
>>> http://www.tomshardware.com/reviews/evga-super-super-clocked-gtx-960,4063-3.html
>>>
>>>
>>>
>>>
>>> --
>>>
>>> Szilárd
>>>
>>>
>>>
>>> On Tue, Jun 30, 2015 at 7:31 PM, Alex <nedomacho at gmail.com> wrote:
>>>
>>>
>>> Well, I don't have one like this. What I have instead is this:
>>>
>>>
>>> 1. A single 6-pin directly from the PSU.
>>>
>>> 2. A single molex to 6-pin (my PSU does provide one molex).
>>>
>>> 3. Two 6-pins to a single 8-pin converter going to the card.
>>>
>>>
>>> In other words, I can populate both 6-pins on the 6-8 converter, just
>>> not sure about the pinouts in this case.
>>>
>>>
>>> Not good?
>>>
>>>
>>> Alex
>>>
>>>
>>>
>>>   >
>>>
>>> What I meant is this: http://goo.gl/8o1B5P
>>>
>>>
>>> That is 2x molex -> 8pin PCI-E. A single molex may not be enouhg.
>>>
>>>
>>>
>>> --
>>>
>>> Szilárd
>>>
>>>
>>>
>>> On Tue, Jun 30, 2015 at 7:10 PM, Alex <nedomacho at gmail.com> wrote:
>>>
>>>
>>> It is a 4-core CPU, single GPU box, so I doubt I will be running more
>>>
>>> than one at a time. We will very likely get a different PSU, unless...
>>>
>>> I do have a molex to 6 pin concerter sitting on this very desk. Do you
>>>
>>> think it will satisfy the card? I just don't know how much a single
>>>
>>> molex line delivers. If you feel this should work, off to installing
>>>
>>> everything I go.
>>>
>>>
>>> Thanks a bunch,
>>>
>>> Alex
>>>
>>>
>>> SP> First of all, unless you run multiple independent simulations on the
>>> same
>>>
>>> SP> GPU, GROMACS runs alone will never get anywhere near the peak power
>>>
>>> SP> consumption of the GPU.
>>>
>>>
>>> SP> The good news is that NVIDIA has gained some sanity and stopped
>>> blocking
>>>
>>> SP> GeForce GPU info in nvidia-smi - although only for newer cars, but
>>> it does
>>>
>>> SP> work with the 960 if you use a 352.xx driver:
>>>
>>> SP> +------------------------------------------------------+
>>>
>>>
>>> SP> | NVIDIA-SMI 352.21     Driver Version: 352.21         |
>>>
>>>
>>> SP>
>>> |-------------------------------+----------------------+----------------------+
>>>
>>> SP> | GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile
>>> Uncorr.
>>>
>>> SP> ECC |
>>>
>>> SP> | Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util
>>> Compute
>>>
>>> SP> M. |
>>>
>>> SP>
>>> |===============================+======================+======================|
>>>
>>> SP> |   0  GeForce GTX 960     Off  | 0000:01:00.0      On |
>>>
>>> SP>  N/A |
>>>
>>> SP> |  8%   45C    P5    15W / 130W |   1168MiB /  2044MiB |     31%
>>>
>>> SP>  Default |
>>>
>>> SP>
>>> +-------------------------------+----------------------+----------------------+
>>>
>>>
>>>
>>> SP> A single 6-pin can deliver 75W, an 8-pin 150W, so in your case, the
>>> hard
>>>
>>> SP> limits of what your card can pull is 75W from the PCI-E slow + 150W
>>> from
>>>
>>> SP> the cable = 225 W. With a single 6-pin cable you'll only get ~150W
>>> max.
>>>
>>> SP> That can be OK if your card does not pull more power (e.g. the above
>>>
>>> SP> non-overclocked card would be just fine), but as your card is
>>> overclocked,
>>>
>>> SP> I'm not sure it won't peak above 150W.
>>>
>>>
>>> SP> You can try to get a molex -> PCI-E power cable converter.
>>>
>>>
>>>
>>> SP> --
>>>
>>> SP> Szilárd
>>>
>>>
>>>
>>> SP> On Mon, Jun 29, 2015 at 9:56 PM, Alex <nedomacho at gmail.com> wrote:
>>>
>>>
>>> >> Hi all,
>>>
>>> >>
>>>
>>> >> I have a bit of a gromacs-unrelated question here, but I think this
>>> is a
>>>
>>> >> better place to ask it than, say, a gaming forum. The Nvidia GTX 960
>>> card
>>>
>>> >> we got here came with an 8-pin AUX connector on the card side, which
>>>
>>> >> interfaces _two_ 6-pin connectors to the PSU. It is a factory
>>> superclocked
>>>
>>> >> card. My 525W PSU can only populate _one_ of those 6-pin connectors.
>>> The
>>>
>>> >> EVGA website states that I need at least 400W PSU, while I have 525.
>>>
>>> >>
>>>
>>> >> At the same time, I have a dedicated high-power PCI-e slot, which on
>>> the
>>>
>>> >> motherboard says "75W PCI-e". Do I need a different PSU to populate
>>> the AUX
>>>
>>> >> power connector completely? Are these runs equivalent to drawing max
>>> power
>>>
>>> >> during gaming?
>>>
>>> >>
>>>
>>> >> Thanks!
>>>
>>> >>
>>>
>>> >> Alex
>>>
>>> >> --
>>>
>>> >> Gromacs Users mailing list
>>>
>>> >>
>>>
>>> >> * Please search the archive at
>>>
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>>>
>>> >> posting!
>>>
>>> >>
>>>
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>>> >>
>>>
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>>>
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>>>
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>>>
>>> >>
>>>
>>>
>>>
>>> --
>>>
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>>>
>>>
>>>
>>> --
>>>
>>> Best regards,
>>>
>>>  Alex                            mailto:nedomacho at gmail.com
>>> <nedomacho at gmail.com>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> Best regards,
>>>
>>>  Alex                            mailto:nedomacho at gmail.com
>>> <nedomacho at gmail.com>
>>>
>>>
>>>
>>>
>>>
>>> --
>>>
>>> Best regards,
>>>
>>>  Alex                            mailto:nedomacho at gmail.com
>>> <nedomacho at gmail.com>
>>>
>>> --
>>> Gromacs Users mailing list
>>>
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>>
>>
>