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Linux founder tells Intel to stop inventing 'magic instructions' and'start fixing real problems'



 
 
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  #1  
Old July 14th 20, 01:39 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
Yousuf Khan[_2_]
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Default Linux founder tells Intel to stop inventing 'magic instructions' and'start fixing real problems'

Linus Torvalds' comments came from this article: https://is.gd/6zpZRL

His comments came in a mailing list (via Phoronix) discussing an article suggesting AVX-512 might not be part of Intel's upcoming Alder Lake architecture. If that comes to pass, it will be just fine by Torvalds.

"I hope AVX512 dies a painful death, and that Intel starts fixing real problems instead of trying to create magic instructions to then create benchmarks that they can look good on. I hope Intel gets back to basics: gets their process working again, and concentrate more on regular code that isn't HPC or some other pointless special case," Torvalds said.

Intel introduced AVX-512 in 2013, initially as part of its Xeon Phi x200 and Skylake-X processor lines. It has also found its way into more current CPU architectures, including Ice Lake.

The instruction set is designed to bolster performance in various types of workloads, such as scientific simulations, financial analytics, artificial intelligence, data compression, and other tasks that can benefit from more robust floating point operations.

Nevertheless, Torvalds views AVX-512 as an example of "special-case garbage," noting that in regards to floating point performance, "absolutely nobody cares outside of benchmarks."

"I absolutely detest FP benchmarks, and I realize other people care deeply. I just think AVX-512 is exactly the wrong thing to do. It's a pet peeve of mine. It's a prime example of something Intel has done wrong, partly by just increasing the fragmentation of the market," Torvalds said.


I think he's absolutely right, and previously we didn't see how much
Intel was wasting its time making these AVX instructions because it's
gaping security flaws were not yet known. We just assumed that the more
sophisticated these floating-point instructions got, the more power they
must draw naturally. But previous generations of FP instructions stayed
well within the power envelope of the processor, whereas these AVX
instructions have been known to go well outside the standard power envelope.

Yousuf Khan
  #2  
Old July 15th 20, 07:42 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
VanguardLH[_2_]
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Default Linux founder tells Intel to stop inventing 'magic instructions' and 'start fixing real problems'

Yousuf Khan wrote:

Linus Torvalds' comments came from this article: https://is.gd/6zpZRL


Full URL:
https://www.pcgamer.com/linux-founde...al-problems%2F

Linus is known for publishing his tirades on Windows, and even on Linux
variants. He lambasts everyone.

Tweaking hardware to look good in benchmarks is news to you? Video chip
makers have been doing this forever, making their hardware or firmware
look better in particular benchmarks (sometimes their own benchmarks
tweaked for their hardware) but for which the benchmarks have no
practical implementation illustrating actual performance in real use.

AVX wasn't just about improving FP instructions. The number of cores
available back then was maybe up to 4 allowing concurrent thread
processing. With more cores to parallelize the computing, AVX becomes
less necessary. The latest CPUs (although far outside the consumer
price range) have 64 cores, maybe more. Sorry, but bitching in
hindsight is the easy way to look superior. I don't see Linux bitching
back *then* when AVX showed up. His forward-looking crystal ball was
just as cloudy as everyone else's. So, how many cores were in your home
computer back in 2013 when AVX came out? AVX isn't just about upping
the bit-width of FP calculations, but also about parallelization. How
many desktops nowadays have any apps on them that can use all 4 cores?

Not all CPUs are waiting to do something for end users. Some are
involved in highly complex computing, like animated computer graphics.
You think Zootopia was composed on a home computer? So, you think Intel
(or AMD) are going to tool up for a completely separate production line
for consumer vs high-graphics design platforms? There is an economy in
production by reusing existing manufacturing processes. Do consumer
platforms utilize AVX? Rarely. Why didn't Linus bitch when Intel added
Streaming SIMD Extensions (SSE)? How about all those non-gaming users
that don't care even about the old SSE extensions? Oh my God, the CPU
has something they don't need.

I suppose next Linus will bitch about increased parallelization in
Mozilla's Firefox. The next engine, Servo, takes advantage of the
memory safety and concurrency features of the Rust programming language.
Servo will use parallelism by using more cores for the rendering engine,
layout, HTML parsing, image processing, decoding, and other tasks that
can be isolated (into separate processes or threads to run on more
cores). Servo also makes further use of GPU-assisted acceleration, so
code running on a different processor. Would the GPU be needed if there
more core CPUs (real or multi-core) to parallelize the FP instructions?

I think GPU-assisted acceleration in web browsers started back in 2010,
but was just for web browsers. I remember some other apps used the GPU
for faster FP processing, but they seemed few and far between. More
video games are using AVX (AVX 2 more than AVX 512) since it is part of
the DirectX12 API. LOTS of users play video games on their home
computers, so AVX is really not that rare for use on low-end computing
platforms. AVX used to be shunned by game devs due to complexity in
coding.

Scalar, non-AVX :

void interpolate(vectorvectorint& mat)
{
for(int i=2; imat.size()-1; i=i+2)
for(int j=0; jmat[0].size(); j++)
{
mat[i][j] = mat[i-1][j] + 0.5f * (mat[i+1][j] - mat[i-1][j]);
}
}


Using AVX:

void interpolate_avx(vectorvectorint& mat)
{
for(int i=2; imat.size()-1; i=i+2)
for(int j=0; jmat[0].size(); j=j+8)
{
_mm256_storeu_si256((__m256i *)&mat[i][j],
_mm256_cvtps_epi32(_mm256_add_ps(_mm256_mul_ps(_mm 256_sub_ps(_mm256_cvtepi32_ps(_mm256_loadu_si256(( __m256i
*)&mat[i+1][j])), _mm256_cvtepi32_ps(_mm256_loadu_si256((__m256i
*)&mat[i-1][j]))), _mm256_set1_ps(0.5f)),
_mm256_cvtepi32_ps(_mm256_loadu_si256((__m256i *)&mat[i-1][j])))));
}
}

However, when mandated to programmers to code a game for maximum
performance, the AVX code runs 6.5 times faster! Simple coding with
slower performance, or complicated coding with faster performance. The
tradeoff is more cost in coding work, debugging, and optimizing hence
more time to achieve faster performance. Considering have video games
have upped the number of moving objects, physics modeling, and moving
texture change, some video games have insane requirements compared to
games dated over a decade ago.

Video games are real use of AVX. It's not just making benchmarks look
better. Guess Linus doesn't have bleeding edge hosts (in technology and
to his pocket) on which to run the most demanding video games. Is Linus
even a gamer? Oh wait, yeah, not that big a selection for Linux.
  #3  
Old July 15th 20, 07:48 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
Brian Gregory[_2_]
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Posts: 6
Default Linux founder tells Intel to stop inventing 'magic instructions' and 'start fixing real problems'

On 15/07/2020 19:42, VanguardLH wrote:
Is Linus even a gamer? Oh wait, yeah, not that big a selection for Linux.


He isn't anyway.

--
Brian Gregory (in England).
  #4  
Old July 16th 20, 02:37 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
Yousuf Khan[_2_]
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Posts: 1,296
Default Linux founder tells Intel to stop inventing 'magic instructions'and 'start fixing real problems'

On 7/15/2020 2:42 PM, VanguardLH wrote:
Not all CPUs are waiting to do something for end users. Some are
involved in highly complex computing, like animated computer graphics.
You think Zootopia was composed on a home computer? So, you think Intel
(or AMD) are going to tool up for a completely separate production line
for consumer vs high-graphics design platforms? There is an economy in
production by reusing existing manufacturing processes. Do consumer
platforms utilize AVX? Rarely. Why didn't Linus bitch when Intel added
Streaming SIMD Extensions (SSE)? How about all those non-gaming users
that don't care even about the old SSE extensions? Oh my God, the CPU
has something they don't need.


Well, no, the SSE extensions were a big improvement over the old
stack-based FPU model. Directly accessible FP registers rather than
pushing and popping indirectly off of a stack. Even AMD's 3DNow achieved
this, requiring even less changes to the hardware (it just fixed the
existing FPU stack model), although AMD did not yet have sufficient
marketshare to push it widely onto the market. I think the point Linus
is making is that AVX takes FPU's to a state that no one asked for. When
the first version of AVX came out, and no one used it, well okay just a
mistake, then the second version came out, hoping that it would correct
the deficiencies of the first one, still kind of understandable. When
even that one wasn't used, and now we're at like version 3 or 4, none of
which are being used, then that's obviously gone too far.

Yousuf Khan
  #5  
Old July 16th 20, 08:19 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default Linux founder tells Intel to stop inventing 'magic instructions' and 'start fixing real problems'

Yousuf Khan wrote:

On 7/15/2020 2:42 PM, VanguardLH wrote:
Not all CPUs are waiting to do something for end users. Some are
involved in highly complex computing, like animated computer graphics.
You think Zootopia was composed on a home computer? So, you think Intel
(or AMD) are going to tool up for a completely separate production line
for consumer vs high-graphics design platforms? There is an economy in
production by reusing existing manufacturing processes. Do consumer
platforms utilize AVX? Rarely. Why didn't Linus bitch when Intel added
Streaming SIMD Extensions (SSE)? How about all those non-gaming users
that don't care even about the old SSE extensions? Oh my God, the CPU
has something they don't need.


Well, no, the SSE extensions were a big improvement over the old
stack-based FPU model. Directly accessible FP registers rather than
pushing and popping indirectly off of a stack. Even AMD's 3DNow achieved
this, requiring even less changes to the hardware (it just fixed the
existing FPU stack model), although AMD did not yet have sufficient
marketshare to push it widely onto the market. I think the point Linus
is making is that AVX takes FPU's to a state that no one asked for. When
the first version of AVX came out, and no one used it, well okay just a
mistake, then the second version came out, hoping that it would correct
the deficiencies of the first one, still kind of understandable. When
even that one wasn't used, and now we're at like version 3 or 4, none of
which are being used, then that's obviously gone too far.

Yousuf Khan


Already pointed out: your "none of which are being used" is wrong. It
is being used. Video games use it, and those are not rare on Windows
platforms. Any game using DirectX 12 are utilizing AVX2. Scientific,
statistical, financial, encryption, and other programs can use it. Any
program using .NET Framework can use AVX. The latest versions of
Prime95 are optimized to use AVX. While it is used to stress test, that
was not its original or current intent which was to discover prime
numbers. Is prime hunting something that home users do? Of course not,
but it illustrates AVX *is* used.

https://www.tomshardware.com/reviews...de,5461-2.html
"By default, Prime95 automatically selects the newest instruction set
extension, such as AVX, AVX2, or even AVX-512."

Your claim AVX is not used is false.

To test, go into the BIOS settings and change the AVX offset, and then
monitor the core frequencies, like with MSI's Afterburner. Surprise, a
lot of video games use AVX. You'll see the core frequencies go down
relative to the AVX offset when running an AVX-enabled program. I don't
play many new games (I still wish the Thief series keep evolving since
stealth is so poorly done in newer games), but have read SofTR,
Darksiders 3, Monster Hunter Word, AC: Odyssey, and Overwatch use AVX.
Overclockers trying to maintain the highest but stable clock rates whine
when core frequencies drop due to AVX, and have to change the AVX offset
to up the freqs.

https://www.google.com/search?q=over...20avx%20offset

If the games weren't using AVX, overclockers wouldn't be stymied over
the reduction in core freqs (and possible instability from vcore
reduction).

https://www.youtube.com/watch?v=BXBSVT9lpGw

Notice the AVX mode has higher frame rates. Also, it seems the right
side (for AVX) seems sharper overall. Timemark 2:23 starts the charts.
Later the author shows AVX doesn't improve performance in all games that
implement AVX. Sometimes AVX helps, sometimes not (but it's not worse).
I'm not into game programming, so I'll let someone else expert in that
note why AVX doesn't do better than SSE.
  #6  
Old July 18th 20, 05:18 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
Yousuf Khan[_2_]
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Posts: 1,296
Default Linux founder tells Intel to stop inventing 'magic instructions'and 'start fixing real problems'

On 7/16/2020 3:19 PM, VanguardLH wrote:
Already pointed out: your "none of which are being used" is wrong. It
is being used. Video games use it, and those are not rare on Windows
platforms. Any game using DirectX 12 are utilizing AVX2. Scientific,
statistical, financial, encryption, and other programs can use it. Any
program using .NET Framework can use AVX. The latest versions of
Prime95 are optimized to use AVX. While it is used to stress test, that
was not its original or current intent which was to discover prime
numbers. Is prime hunting something that home users do? Of course not,
but it illustrates AVX *is* used.


No, there is a difference between "are utilizing" and "can use". You
used both terms in different sentences up above, probably because you're
not actually sure which one it is, and you wanted to CYA.

"Are utilizing" implies that the games have no choice in the matter, and
they are using AVX even if they don't know it. This would presumably
mean that AVX is being used within the DirectX 12 API itself, and
operates in the background regardless of direct utilization by the game
itself.

That is not how the DX12 API operates. It is a bare-metal API, allowing
the games themselves to control most low-level aspects of the visual
production. This is unlike DX11 the previous API, which was more
hands-on, controlling the low-level aspects. I could see if DX11 had
been further developed, they perhaps might have started to use AVX
within the API itself to help some aspects of performance. But they went
in the completely opposite direction with DX12, I really don't see how
AVX benefits the DX12 low-level API, as it's mainly just a series of
calls to the GPU. For DX12, the "can use" AVX is the appropriate term,
not the "are utilizing".

But even within the game itself over the level of the API, AVX
utilization is very rare. Games could use AVX even under DX11 or even
DX9 or 10 beforehand, but it just didn't use it in the API. There was no
prohibition of using AVX within the application itself. These days they
are more likely to pass off most FP calculations off to the GPU than to
try to do it within the CPU anymore, so AVX is dead in the water.

https://www.tomshardware.com/reviews...de,5461-2.html
"By default, Prime95 automatically selects the newest instruction set
extension, such as AVX, AVX2, or even AVX-512."

Your claim AVX is not used is false.


On the contrary, this exactly proves my point. Torvalds was complaining
about how it's only being used in benchmarks but no real apps. Prime95
is exactly an example of a benchmark and stress testing app. Nobody is
actually using Prime95 for anything other than stress testing and
benchmarking. It's not like as if you're going to be finding any new
prime numbers with a PC anymore, those have now firmly entered the realm
of supercomputers/HPC.

Yousuf Khan
  #7  
Old July 19th 20, 02:46 AM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default Linux founder tells Intel to stop inventing 'magic instructions' and 'start fixing real problems'

Yousuf Khan wrote:

Prime95 is exactly an example of a benchmark and stress testing app.
Nobody is actually using Prime95 for anything other than stress
testing and benchmarking.


Yep, elide over the intent of the authors of Prime95, because that would
be another example of several shown where AVX is used.
  #8  
Old July 16th 20, 07:35 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
T[_6_]
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Posts: 49
Default Linux founder tells Intel to stop inventing 'magic instructions' and 'start fixing real problems'

On 2020-07-15 11:42, VanguardLH wrote:
Is Linus
even a gamer? Oh wait, yeah, not that big a selection for Linux.


Linux is not tied with Windows for gaming. Take
a gander at:

Fedora 31 | Features, Gaming, and New Daily Driver
https://www.youtube.com/watch?v=1P8oBlOTBho
  #9  
Old July 16th 20, 09:28 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
T[_6_]
external usenet poster
 
Posts: 49
Default Linux founder tells Intel to stop inventing 'magic instructions'and 'start fixing real problems'

On 2020-07-16 11:35, T wrote:
isĀ*not


"is now"

Stinking typos

  #10  
Old July 16th 20, 10:01 PM posted to alt.windows7.general,alt.comp.os.windows-10,comp.sys.intel,comp.sys.ibm.pc.hardware.chips
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default Linux founder tells Intel to stop inventing 'magic instructions' and 'start fixing real problems'

T wrote:

VanguardLH wrote:

Is Linus even a gamer? Oh wait, yeah, not that big a selection for
Linux.


Linux is not tied with Windows for gaming. Take
a gander at:

Fedora 31 | Features, Gaming, and New Daily Driver
https://www.youtube.com/watch?v=1P8oBlOTBho


You didn't provide a timemark for the related content, and I wasn't
going to watch all of the 22 minute video, so I moved the slider to skim
through it. The author started talking about Steam on Linux which could
now detect the native OS platform to know which game titles to present.
Steam represents about 78% of the marketshare for computer games. I saw
something about them using a compatibility shim to run Windows games on
Linux platforms eliminating the need to run Steam and the Windows games
inside of WINE. Wonder how the benchmarks reflect the performance of a
Windows game running inside of WINE versus running the Windows game atop
Steam's shim.

https://itsfoss.com/steam-play/

Oh, so Steam Play simply provides a fork of WINE as its shim between the
native OS platform and the Windows-only game. The Windows games will
likely be impacted the same whether ran inside of WINE or Steam's
variant of WINE. I didn't even bother to address running anything
Windows inside of WINE or via any other emulation layer, like VMWare
Player for Linux running Windows as a guest OS and then running a
Windows game inside of that virtual machine. That something is doable
doesn't mean it should be.

That still means the games were *not* developed for the Linux platform.
They were written for the Windows platform. Guess I should've qualified
my statement by saying:

"Oh wait, yeah, not that big a selection of native Linux games. "

Do hardcore gamers even bother with WINE? Conversely, everything Linux
can be played on Windows, too, so the user could use a Windows platform
to play native Windows games and emulated Linux games. Is there much
draw for that scenario? You can even play Android apps on Windows by
using a shim aka emulator, like Bluestacks. There's native-on-native,
and then there are less-than-ideal workarounds.
 




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