Re: [gentoo-user] Re: new computer : any advice ?

[Rich Freeman]

On Thu, Sep 10, 2015 at 8:20 AM, james  wrote:
> I think most folks when purchasing a workstation include a graphics
> card on the list of items to include. So my suggestions where geared
> towards informing folks about some of the new features of gcc that
> may intice them to consider the graphics card resources in an
> expanded vision of general resources for their workstation.

Sure, but keep in mind depreciation.

If all you need today is a $30 graphics card, then you probably should
just spend $30.  If you think that software will be able to use all
kinds of fancy features on a $300 graphics card in two years, you
should just spend $30 today, and then wait two years and buy the fancy
graphics card on clearance for $10.

It is pretty rare that it is a wise move to spend money today on
computer hardware that you don't have immediate plans to use.  The
only time it might make sense is if some kind of QA process means that
you're going to spend a lot more money on re-qualifying your system
after the upgrade than it would cost to just do it once and overspend
on hardware.  However, in general I'm not a big fan of those kinds of
QA practices in the first place.

-- 
Rich

Re: [gentoo-user] Re: new computer : any advice ?

[Gevisz]

On Thu, 10 Sep 2015 12:20:39 + (UTC) james  wrote:

> Fernando Rodriguez  outlook.com> writes:
> 
> > > albeit in it's infancy. Naturally it's going to take a while to 
> > > become mainstream useful; but that more like a year or 2, at most.
> > 
> > The value I see on that technology for desktop computing is that we
> > get the GPUs for what they're made (graphics processing) but their
> > resources go unused by most applications, not in buying powerful
> > GPUs for the purpose of offloading general purpose code, if that's
> > the goal you're better off investing in more general purpose cores
> > that are more suited for the task.

It is true.
 
> I think most folks when purchasing a workstation include a graphics
> card on the list of items to include. So my suggestions where geared
> towards informing folks about some of the new features of gcc that
> may intice them to consider the graphics card resources in an
> expanded vision of general resources for their workstation.
> 
> > To trully take advantage of the GPU the actual algorithms need to be
> > rewritten to use features like SIMD and other advanced parallelization
> > features, most desktop workloads don't lend themselves for that kind
> > of parallelization.

And it is also true.

> Not true if what openacc hopes to achived indeed does become a reality.

Hopes almost never becomes a reality.

> Currently, you are most correct.

Absolutely correct.

...

> 
> When folks buy new hardware, it is often a good time to look at what
> is on the horizon for computers they use.

I also considered "what is on the horizon" when bought a brand new
ATI Radeon R4770 graphic card about 6 years ago for computing purposes.

In half a year it was discovered that it has much worse performance than
ATI guys hoped for and, to improve it, they have to rewrite their proprietary
drive for this graphic card.

Instead of doing it, they just shamelessly dropped the support of the parallel
computing feature of this graphic card in all subsequent versions of their 
drive.

And as far as I know, no open source drive have ever supported the parallel
computing feature of this graphic card as well.

So, it was just a waste of money. Even more: I almost never worked at my 
assembled
almost 7 year-old 4-core AMD computer with this graphic card as for all other
purposes I prefer to work at my 10 year-old 2-core AMD computer with a very 
cheap
on-board video card. Just to avoid extra heating and aircraft noise produced by 
R4770.

So, Rich Freeman was absolutely right when he wrote in reply to your words 
above that

> If all you need today is a $30 graphics card, then you probably should
> just spend $30.  If you think that software will be able to use all
> kinds of fancy features on a $300 graphics card in two years, you
> should just spend $30 today, and then wait two years and buy the fancy
> graphics card on clearance for $10.

> It is pretty rare that it is a wise move to spend money today on
> computer hardware that you don't have immediate plans to use.

Re: [gentoo-user] Re: new computer : any advice ?

[Gevisz]

On Thu, 10 Sep 2015 21:12:37 + (UTC) james  wrote:

> Gevisz  gmail.com> writes:
> 
> > on-board video card. Just to avoid extra heating and aircraft noise 
> > produced by R4770.
> 
> Fanless video cards are wonderful. I have had many over the years but this
> one is still my (silent) favorite::
> 
> 01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI]
> Cape Verde PRO [Radeon HD 7750 / R7 250E]

Thank you for information.

Never say never, but according to my current mood
(which is unchanged for the last 5 years already :),
I will never buy ATI video card again.

And not because of noise and heating of ATI Radeon R4770
but because ATI shamelessly dropped support of their much
advertised parallel computing feature for this video card.

And I am not a fan of NVidia either.

Only small, cheap and fanless on-board video cards
to just manage the monitor!

At least for the next 12 or 15 years. :)
 
> I did notice in a gentoo blog that openmp is a testing option for Clang-3.7
> now? [1]
> 
> Try not to loose faith, we all have had bad experiences, but clustering,
> distributed and systems aggregation codes are rapidly coalescing into
> something wonderful, so . keep the faith.. bro.
> 
> ;-)   
> 
> wwr,
> James
> 
> 
> [1] http://blog.cafarelli.fr/2015/09/testing-clang-3-7-0-openmp-support/
> 
> 
> 
> 

Re: [gentoo-user] Re: new computer : any advice ?

[Fernando Rodriguez]

On Wednesday, September 09, 2015 9:52:55 PM james wrote:
> Jeremi Piotrowski  gmail.com> writes:
> 
> > No, and yes. Compilation is not affected in any way and runtime
> > performance can only be improved _if_ this stuff is explicitly used within
> > the code.
> 
> Yes this is all new and a work in progress. I do not think it will be
> gcc-6 that makes the difference in a few years. But folks should be aware
> and look for codes that are accelerated via usage of GPU resources.
> Remember this all started about hardware purchase and future benefits.
> It's definitely not commodity usage atm.
> 
> 
> > Meaning you would feel a difference in no less then 5 years when gcc-6 is
> > widely used and accelerator support is not restricted to intel MIC and
> > nvidia gpus. James is getting a bit ahead of himself calling this a
> > "game changer" - yeah... not really right now.
> 
> It's not as restricted as you indicate amd, intel, nividia and others like
> arm (Mali and such) are working to support there hardware under the openacc
> code extension now in gcc-5. Granted the more powerful your GPU resources
> are the more they can contribute. This stuff use to only work with
> vendor supplied compilers and sdks, now it's finally available in gcc,
> albeit in it's infancy. Naturally it's going to take a while to 
> become mainstream useful; but that more like a year or 2, at most.

The value I see on that technology for desktop computing is that we get the 
GPUs for what they're made (graphics processing) but their resources go unused 
by most applications, not in buying powerful GPUs for the purpose of offloading 
general purpose code, if that's the goal you're better off investing in more 
general purpose cores that are more suited for the task.

To trully take advantage of the GPU the actual algorithms need to be rewritten 
to use features like SIMD and other advanced parallelization features, most 
desktop workloads don't lend themselves for that kind of parallelization. That 
is why despite similar predictions about how OpenMP-like parallel models would 
obsolete the current threads model since they where first proposed, it hasn't  
happened yet.

Even for the purpose of offloading general purpose code, it seems with all the 
limitations on OpanACC kernels few desktop applications can take advantage of 
it (and noticeably benefit from it) without major rewrites. Off the top of my 
head audio, video/graphics encoders, and a few other things that max out the 
cpu and can be broken into independent execution units.

-- 
Fernando Rodriguez

Re: [gentoo-user] Re: new computer : any advice ?

[Stefan G. Weichinger]

On 09.09.2015 21:35, Jeremi Piotrowski wrote:

> tldr: don't buy a dedicated gpu just because you read something on a
> mailing list ;)

yep :-)

Re: [gentoo-user] Re: new computer : any advice ?

[Stefan G. Weichinger]

On 09.09.2015 20:01, Stefan G. Weichinger wrote:
> Digging up that thread now somewhere ...

Ah, I even participated then ;-)

AFAI understand gcc-5 should compile faster?
And generate faster code in some cases?

looking at genlop -t I can't really spot speedups in the last months.

With gcc-5.2.0 as I have here right now:

5.2.0(5.2)^s(20:52:29 18.07.2015)(cxx fortran multilib nls openmp
sanitize -altivec -awt -cilk -debug -doc -fixed-point -gcj -go -graphite
-hardened -libssp -multislot -nopie -nossp -nptl -objc -objc++ -objc-gc
-regression-test -vanilla)

... does it use this new stuff anyway, do we need a specific USE-flag
enabled (I can't spot it, looking for something like "acc" or "rdma"
;-)), do we need specific CFLAGS .. ?

just curious.

btw: might be a projection but for some times back I noticed that my
gentoo installation got somehow "snappier" in a way. Might relate to my
rebuilding with gcc-5.x (and overall improvement of hundreds of
packages, sure).

Re: [gentoo-user] Re: new computer : any advice ?

[Stefan G. Weichinger]

Am 2015-09-09 um 04:20 schrieb James:


I have posted several links on the subject previously [1]; here's one [2].


[..]


If you can afford it, get a mobo that supports DDR-4.
Right now the AMD-HBM Fury-X is the video card with the
highest bandwidth for a memory buss on a video card, if
you can find one for sale:: limited production right now.

RDMA Remote Dynamic Memory Access is the principal finally available
in gcc


Thanks for the pointers, I will read through that thread soon.
So this means chosing CPU *and* GPU accordingly :-)

I didn't plan to buy a separate video card at all as my usage is quite 
office/terminal-style without gaming or video stuff. The integrated 
graphics of modern core-i7xxx should be enough to run my 2 
24-inch-monitors. But if the GPU helps speeding up things ... I have to 
consider this as well.


Digging up that thread now somewhere ...

Stefan

Re: [gentoo-user] Re: new computer : any advice ?

[Mick]

On Wednesday 09 Sep 2015 19:01:24 Stefan G. Weichinger wrote:
> Am 2015-09-09 um 04:20 schrieb James:
> > I have posted several links on the subject previously [1]; here's one
> > [2].
> 
> [..]
> 
> > If you can afford it, get a mobo that supports DDR-4.
> > Right now the AMD-HBM Fury-X is the video card with the
> > highest bandwidth for a memory buss on a video card, if
> > you can find one for sale:: limited production right now.
> > 
> > RDMA Remote Dynamic Memory Access is the principal finally available
> > in gcc
> 
> Thanks for the pointers, I will read through that thread soon.
> So this means chosing CPU *and* GPU accordingly :-)
> 
> I didn't plan to buy a separate video card at all as my usage is quite
> office/terminal-style without gaming or video stuff. The integrated
> graphics of modern core-i7xxx should be enough to run my 2
> 24-inch-monitors. But if the GPU helps speeding up things ... I have to
> consider this as well.
> 
> Digging up that thread now somewhere ...
> 
> Stefan

I built last Christmas a Kaveri APU based PC, with two 23" monitors and no 
external GPU.  This is a PC used as a workstation for coding, image processing 
and the odd video transcoding.  No gaming.  Using stable radeon driver.  The 
performance of this machine has really impressed me when compiling packages, 
but I don't have the latest generation i7 to compare it with.  Unlike noisy 
discrete GPUs this thing is really quiet and doesn't consume much power 
either.  The Asus MoBo has a port for an external GPU, but I don't think I 
will ever bother getting one - certainly not new.  ;-)

I have been thinking that the better compiling performance compared to my 
other older PCs can't just be CPU specific, it must be all these additional 
HSA-enabled compute cores that are doing some of the heavy lifting.  I don't 
know how to check this though.

-- 
Regards,
Mick


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Re: [gentoo-user] Re: new computer : any advice ?

[Jeremi Piotrowski]

On Wed, 9 Sep 2015, Stefan G. Weichinger wrote:

> On 09.09.2015 20:01, Stefan G. Weichinger wrote:
> > Digging up that thread now somewhere ...
>
> Ah, I even participated then ;-)
>
> AFAI understand gcc-5 should compile faster?
> And generate faster code in some cases?

No, and yes. Compilation is not affected in any way and runtime
performance can only be improved _if_ this stuff is explicitly used within
the code.

Meaning you would feel a difference in no less then 5 years when gcc-6 is
widely used and accelerator support is not restricted to intel MIC and
nvidia gpus. James is getting a bit ahead of himself calling this a
"game changer" - yeah... not really right now.

Right now this functionality is a toy for the HPC community and will stay
that way. To use it you have to build a separate offloading compiler, need
custom code used by few, and expensive hardware. The tree ebuild doesn't
even provide a way for enabling the accelerator support.


>
> ... does it use this new stuff anyway, do we need a specific USE-flag
> enabled (I can't spot it, looking for something like "acc" or "rdma"
> ;-)), do we need specific CFLAGS .. ?
>
> just curious.

I can't speak for RDMA (can't find any mention of it in gcc) because
that's an even more exotic thing than plain old accelerator support
(unless you run infiniband at home...), but the flags are:

-fopenmp
-foffload
-fopenacc

However enabling them is as useful as having CFLAGS=-fopenmp currently. It
changes __nothing__ unless an application has openmp annotations, and the
ones that do should already provide a means of doing so in the build
system.

tldr: don't buy a dedicated gpu just because you read something on a
mailing list ;)

Re: [gentoo-user] Re: new computer : any advice ?

[Alan McKinnon]

On 09/09/2015 20:01, Stefan G. Weichinger wrote:
> Am 2015-09-09 um 04:20 schrieb James:
> 
>> I have posted several links on the subject previously [1]; here's one
>> [2].
> 
> [..]
> 
>> If you can afford it, get a mobo that supports DDR-4.
>> Right now the AMD-HBM Fury-X is the video card with the
>> highest bandwidth for a memory buss on a video card, if
>> you can find one for sale:: limited production right now.
>>
>> RDMA Remote Dynamic Memory Access is the principal finally available
>> in gcc
> 
> Thanks for the pointers, I will read through that thread soon.
> So this means chosing CPU *and* GPU accordingly :-)
> 
> I didn't plan to buy a separate video card at all as my usage is quite
> office/terminal-style without gaming or video stuff. The integrated
> graphics of modern core-i7xxx should be enough to run my 2
> 24-inch-monitors. But if the GPU helps speeding up things ... I have to
> consider this as well.

I've done exactly that on my i7 laptop for ages now. It usually runs
it's own 1920 display and an external monitor of same resolution, and
has this hardware:

00:02.0 VGA compatible controller: Intel Corporation 4th Gen Core
Processor Integrated Graphics Controller (rev 06)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc.
[AMD/ATI] Venus XT [Radeon HD 8870M / R9 M270X/M370X]

I use the intel video driver and it's been more than a year since I
built a kernel with radeon :-)

The intel gpu manages full HD video and funky plasma5 effects just fine
at a fraction of the battery usage of the radeon. These days I ask
myself: if I'm not gaming at insane frame rates, or using cuda, then why
do I need the radeon power at all?



-- 
Alan McKinnon
alan.mckin...@gmail.com

Re: [gentoo-user] Re: new computer : any advice ?

[Stefan G. Weichinger]

Am 2015-09-08 um 17:32 schrieb James:

> So I'm not really pushing any sort of hardware. But things are changing
> with gcc-5.x 

could you detail this a bit?
Does it need less RAM or what?

I also consider getting a new system later this year, maybe a
core-i7-6xxx or so ...

Re: [gentoo-user] Re: new computer : any advice ?

[Francisco Ares]

2015-09-08 12:51 GMT-03:00 Stefan G. Weichinger :

> Am 2015-09-08 um 17:32 schrieb James:
>
> > So I'm not really pushing any sort of hardware. But things are changing
> > with gcc-5.x
>
> could you detail this a bit?
> Does it need less RAM or what?
>
> I also consider getting a new system later this year, maybe a
> core-i7-6xxx or so ...
>
>
>

Just my 2 cents:

IMHO, high end video cards, OpenCL capable (CUDA for nVidia), will be more
and more used for intensive and massive data manipulation, like audio and
video (image) recognition, which will be (I guess) the base of the future
user interfaces.

So why not get ready right now?  ;-)

Best regards,
Francisco