Hi Aron,
GK104 is mostly toast on the DP front so is not going to rock any boats
unfortunately. However, I can't give you the details for GK110 due to NDA
restrictions but all I can say is do not worry, it 'should' ROCK! - so for
the moment don't get too excited about anything based on GK104 but wait
maybe 6 months or so and things will look rosey. ;-)
I can't say more than that unfortunately but I am smiling. ;-)
All the best
Ross
> -----Original Message-----
> From: Aron Broom [mailto:broomsday.gmail.com]
> Sent: Wednesday, March 28, 2012 10:46 AM
> To: AMBER Mailing List
> Cc: filip fratev
> Subject: Re: [AMBER] GTX680
>
> yeah exactly, I'll keep my fingers crossed. Thanks again for sending
> us
> this info!
>
> On Wed, Mar 28, 2012 at 1:40 PM, Scott Le Grand
> <varelse2005.gmail.com>wrote:
>
> > I wouldn't give up at all. If GK104 had 2x 580 double-precision, I'd
> > already be hitting 1.7x GTX 580 perf on it. And I can't see NVIDIA
> > abandoning the high ground, ever. I can see them providing better
> > differentiation between consumer and Tesla though. After all, what
> games
> > right now make extensive use of GPU double-precision?
> >
> > Scott
> >
> > On Wed, Mar 28, 2012 at 10:30 AM, Aron Broom <broomsday.gmail.com>
> wrote:
> >
> > > Ha, thanks for the correction concerning the consumer cards.
> > >
> > > To follow-up on your point then, do you think you'll be getting an
> > > opportunity to test a GK110 when it comes out and give us the
> scoop? I
> > had
> > > so much hope for the new Keplers, it would be really sad if we have
> to
> > > stick with the older technology. As much as I liked being able to
> buy
> > > cheap consumer cards, I'm fine with the idea of having consumer
> > specialized
> > > cards that deliver for gaming and another set that deliver for
> GPGPU.
> > >
> > > Anyway, I'll keep holding onto the hope that the GK110 gives
> something
> > > amazing like 2x the speed of an M2090. I also heard a rumor, of
> dubious
> > > reliability, that the GK110 would have 384-bit memory BUS rather
> than the
> > > 256 of the 680.
> > >
> > > ~Aron
> > >
> > > On Wed, Mar 28, 2012 at 1:07 PM, Scott Le Grand
> <varelse2005.gmail.com
> > > >wrote:
> > >
> > > > It's *not* artificially crippled. It *never* was. That's the
> sort of
> > > > nonsense you get from reading Charlie Demerjian (whom I can only
> assume
> > > > must have had his family fortune destroyed by speculating in
> NVIDIA
> > > > stock)*. While Teslas and Ge Forces shared the same base chip,
> the
> > > > Tesla-grade chips required all double-precision units to be
> functional
> > > > while a Ge Force only needed 1 out of 4 to work to be shippable.
> So
> > > you're
> > > > getting slightly less functional chips for far less money. And
> if you
> > > > think that's crazy, check out what Intel charges for a 100 MHz
> clock
> > > boost
> > > > on a consumer CPU.
> > > >
> > > > You are correct however that AMBER performance in SPDP mode is
> more or
> > > less
> > > > equivalent between a GTX 570 and an M2070. But that changes
> > dramatically
> > > > in full double-precision mode however where the M2070 is roughly
> 2x
> > > faster
> > > > (go ahead, try it). There's also a hardware bug in Ge Force
> chips that
> > > > breaks parallel runs that has never manifested in Tesla so it's
> not
> > quite
> > > > as black and white.
> > > >
> > > > So I'd say stick with the M2090s for now (or just wait and see
> what
> > GK110
> > > > delivers before making such a call).
> > > >
> > > > Scott
> > > >
> > > >
> > > >
> > > > *He seemed much saner in the 1990s when we were both Atari Jaguar
> > > > developers and talked regularly over IRC. He even stopped by my
> > > apartment
> > > > once apparently while I was at a conference. Oh well, whatever
> floats
> > > his
> > > > boat.
> > > >
> > > > On Wed, Mar 28, 2012 at 9:54 AM, Aron Broom <broomsday.gmail.com>
> > wrote:
> > > >
> > > > > In terms of this double precision hit, how do you think that
> will
> > work
> > > > out
> > > > > on the workstation cards?
> > > > >
> > > > > I know for the Fermi cards for instance, the double precision
> was
> > > > > artificially crippled in the consumer cards (GTX 580) to be 1/4
> of
> > what
> > > > it
> > > > > was in the workstation (M2090). In testing AMBER and other
> programs
> > > > (NAMD)
> > > > > on a GTX 570 and M2070 (almost identical number of cores) I've
> found
> > no
> > > > > real improvement in speed with the M2070, which suggests that
> the 4x
> > > > double
> > > > > precision wasn't entirely needed for AMBER or NAMD.
> > > > >
> > > > > So the question then is: is the low double precision capability
> of
> > the
> > > > 680
> > > > > partially because it has again been artificially crippled, and
> the
> > > > > corresponding workstation cards will actually have enough
> double
> > > > precision
> > > > > performance to show something fantastic?
> > > > >
> > > > > Personally I'm fine with buying up a bunch of GTX570s when
> people are
> > > > > trying to clear out that model, but I know some people who will
> be
> > > > looking
> > > > > to purchase new workstation GPUs soon, and I've love to have a
> good
> > > sense
> > > > > of whether or not they should just continue on with the M2090s.
> > > > >
> > > > > Thanks,
> > > > >
> > > > > ~Aron
> > > > >
> > > > > On Wed, Mar 28, 2012 at 12:33 PM, Scott Le Grand <
> > > varelse2005.gmail.com
> > > > > >wrote:
> > > > >
> > > > > > After a weekend with GTX 680, what I can say is that this is
> a
> > great
> > > > > gaming
> > > > > > GPU with amazing single-precision and texture performance,
> but it
> > has
> > > > the
> > > > > > same overall memory bandwidth as a GTX 580 with significantly
> > > > > > *less*double-precision performance.
> > > > > >
> > > > > > The upshot is that I expect it to only deliver 85-90% of a
> GTX 580.
> > > > And
> > > > > > that's partially because there's no increase in memory
> bandwidth
> > and
> > > > > mostly
> > > > > > because of the regression in double-precision performance.
> And
> > > that's
> > > > a
> > > > > > shame because single-precision *screams* on this chip.
> > > > > >
> > > > > > There are compensated single-precision accumulation
> algorithms that
> > > > could
> > > > > > be used here to ameliorate the performance hit. But this is
> a
> > > > dangerous
> > > > > > precedent to follow IMO that leads to code fragmentation
> because
> > > > > > double-precision on all Fermi-class GPUs was faster, more
> precise,
> > > and
> > > > > > simpler than such algorithms (which themselves where faster
> on GTX
> > > 2xx
> > > > > (see
> > > > > > Tetsu Narumi's work, sigh). This is a nightmare to validate:
> GTX
> > 680
> > > > > > simply shouldn't have regressed on double-precision
> performance.
> > > > > > Hopefully, the next chip won't. That said, this thing
> overclocks
> > > like
> > > > > > crazy and the modder crowd has already doubled the base
> clock. So
> > > > > perhaps
> > > > > > not all hope is lost...
> > > > > >
> > > > > > Scott
> > > > > >
> > > > > >
> > > > > >
> > > > > > On Fri, Mar 23, 2012 at 11:57 AM, Scott Le Grand <
> > > > varelse2005.gmail.com
> > > > > > >wrote:
> > > > > >
> > > > > > > I am very optimistic about GTC680 performance...
> > > > > > >
> > > > > > > That said, anyone who hacks the configure script to make
> the
> > > current
> > > > > code
> > > > > > > run will be severely (an unnecessarily) disappointed.
> Every
> > AMBER
> > > > > kernel
> > > > > > > has been meticulously shoehorned into GTX2xx and GTX5xx
> GPUs.
> > > GTX680
> > > > > is
> > > > > > a
> > > > > > > radical redesign of Fermi (please don't listen to the
> dunderheads
> > > on
> > > > > > review
> > > > > > > sites blathering about matters that's beyond them about
> such
> > > things,
> > > > > > > seriously). That radical redesign has created a much more
> > > efficient
> > > > > GPU
> > > > > > > (I'm expecting the perf/watt on AMBER to hit transwarp as
> opposed
> > > to
> > > > > > merely
> > > > > > > warp drive in the near future) but it's been at the expense
> of
> > 33%
> > > > > higher
> > > > > > > operational latency.
> > > > > > >
> > > > > > > 33% higher operational latency is fine - except that the
> shared
> > > > memory
> > > > > on
> > > > > > > GTX680 is exactly the same as GTX580 and that's leading to
> a ~30%
> > > > > > > performance deficit if one just runs the existing code.
> However,
> > > > there
> > > > > > are
> > > > > > > 2x as many machine registers on GTX680 than on GTX580. Or
> TLDR: I
> > > > need
> > > > > to
> > > > > > > rewrite every single kernel for GTX680 from the ground-up
> to hit
> > > > > > attainable
> > > > > > > performance.
> > > > > > >
> > > > > > > So give me a few weeks, mmkay?
> > > > > > >
> > > > > > > Scott
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > On Fri, Mar 23, 2012 at 11:49 AM, Ross Walker <
> > > ross.rosswalker.co.uk
> > > > > > >wrote:
> > > > > > >
> > > > > > >> Hi Filip,
> > > > > > >>
> > > > > > >> > Hi all,
> > > > > > >> > I was wondering
> > > > > > >> > what we can expect from GTX680 and in general from the
> new
> > > Kepler
> > > > > > line.
> > > > > > >> > I know
> > > > > > >> > that GTX680 is very limited DP, but should be good in SP
> mode.
> > > > Would
> > > > > > we
> > > > > > >> > expect
> > > > > > >> > some speed boost compared to GTX580 and also will it
> work
> > along
> > > > > Amber
> > > > > > >> > 11/12?
> > > > > > >>
> > > > > > >> Amber 11 will NOT support the GTX680 cards (unless you
> hack the
> > > > > > configure
> > > > > > >> script to compile it in what is effectively an emulation
> mode).
> > It
> > > > > will
> > > > > > be
> > > > > > >> too much work to make patch against that. AMBER 12 will
> support
> > > them
> > > > > > but it
> > > > > > >> is going to take around 6 weeks to 2 months to get the
> > > optimization
> > > > > done
> > > > > > >> and a patch released so it won't support the cards at
> release
> > but
> > > it
> > > > > > will
> > > > > > >> as soon as we have the patch ready. I can't really give
> you any
> > > > > > performance
> > > > > > >> expectations right now, only got my first prototype board
> > > yesterday.
> > > > > ;-)
> > > > > > >>
> > > > > > >> Right now if you compile AMBER 12 with PTX support so that
> it
> > will
> > > > at
> > > > > > >> least run on the GTX680 the performance sucks. It is about
> 70%
> > of
> > > a
> > > > > > GTX580.
> > > > > > >> NVIDIA changed the hardware too much (massively increasing
> the
> > > > threads
> > > > > > but
> > > > > > >> also the thread latency) so it will need some work to
> optimize
> > it
> > > > > which
> > > > > > is
> > > > > > >> why I have chosen not to support the cards in AMBER 12
> until we
> > > have
> > > > > > that
> > > > > > >> optimization done. Once it is done I expect considerable
> > > improvement
> > > > > > over
> > > > > > >> GTX580 speeds but can't give you anything concrete right
> now.
> > > > > > >>
> > > > > > >> > P.S. Indeed most
> > > > > > >> > of us will probably wait for GK110, but CUDA capability
> of
> > > GTX680
> > > > is
> > > > > > >> > very limited now.
> > > > > > >>
> > > > > > >> This is probably a good idea, at least you should wait
> until we
> > > have
> > > > > had
> > > > > > >> a chance to get our hands dirty with the GK104 chip. So
> I'd urge
> > > you
> > > > > to
> > > > > > >> wait at least until we have the patch ready for AMBER 12.
> > > > > > >>
> > > > > > >> All the best
> > > > > > >> Ross
> > > > > > >>
> > > > > > >> /\
> > > > > > >> \/
> > > > > > >> |\oss Walker
> > > > > > >>
> > > > > > >> ---------------------------------------------------------
> > > > > > >> | Assistant Research Professor |
> > > > > > >> | San Diego Supercomputer Center |
> > > > > > >> | Adjunct Assistant Professor |
> > > > > > >> | Dept. of Chemistry and Biochemistry |
> > > > > > >> | University of California San Diego |
> > > > > > >> | NVIDIA Fellow |
> > > > > > >> | http://www.rosswalker.co.uk | http://www.wmd-lab.org/ |
> > > > > > >> | Tel: +1 858 822 0854 | EMail:- ross.rosswalker.co.uk |
> > > > > > >> ---------------------------------------------------------
> > > > > > >>
> > > > > > >> Note: Electronic Mail is not secure, has no guarantee of
> > delivery,
> > > > may
> > > > > > >> not be read every day, and should not be used for urgent
> or
> > > > sensitive
> > > > > > >> issues.
> > > > > > >>
> > > > > > >>
> > > > > > >>
> > > > > > >>
> > > > > > >>
> > > > > > >> _______________________________________________
> > > > > > >> AMBER mailing list
> > > > > > >> AMBER.ambermd.org
> > > > > > >> http://lists.ambermd.org/mailman/listinfo/amber
> > > > > > >>
> > > > > > >
> > > > > > >
> > > > > > _______________________________________________
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> > > > > >
> > > > >
> > > > >
> > > > >
> > > > > --
> > > > > Aron Broom M.Sc
> > > > > PhD Student
> > > > > Department of Chemistry
> > > > > University of Waterloo
> > > > > _______________________________________________
> > > > > AMBER mailing list
> > > > > AMBER.ambermd.org
> > > > > http://lists.ambermd.org/mailman/listinfo/amber
> > > > >
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> > > > http://lists.ambermd.org/mailman/listinfo/amber
> > > >
> > >
> > >
> > >
> > > --
> > > Aron Broom M.Sc
> > > PhD Student
> > > Department of Chemistry
> > > University of Waterloo
> > > _______________________________________________
> > > AMBER mailing list
> > > AMBER.ambermd.org
> > > http://lists.ambermd.org/mailman/listinfo/amber
> > >
> > _______________________________________________
> > AMBER mailing list
> > AMBER.ambermd.org
> > http://lists.ambermd.org/mailman/listinfo/amber
> >
>
>
>
> --
> Aron Broom M.Sc
> PhD Student
> Department of Chemistry
> University of Waterloo
> _______________________________________________
> AMBER mailing list
> AMBER.ambermd.org
> http://lists.ambermd.org/mailman/listinfo/amber
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Received on Wed Mar 28 2012 - 14:00:03 PDT
