Article on IA32 (PAE) vs x86_64 Kernel Performance

[Gamingphreek]

http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1

I just saw this article on phoronix just now and I was somewhat surprised that how much the 64bit kernel has improved. I was even more surprised to see that the PAE does, apparently, nothing on that Kernel.

-Kevin

 

[Nothinman]

All PAE does is add an extra level of page tables, I'd be more surprised if it actually had a substantial affect on peformance.

 

[Gamingphreek]

Given that the system can address the full 4GB of memory then, shouldn't performance increase at least slightly when using a large chunk of memory?

 

[Nothinman]

Only if the workload is memory bound, I just scrolled through the article real quick but everything they benchmarked looks like it's CPU bound.

 

[Fox5]

Not too surprising to see some large gains with the 64 bit kernel, afaik the 32 bit kernel is compiled for the generic i686 (few optimizations and doesn't use more recent extensions), the 64 bit kernel is obviously x86-64 which includes sse2 in its minimum spec.
From the few 64 bit atom benchmarks I've seen, it gets absolutely huge performance increases with the 64 bit kernel, which makes it a real shame intel doesn't enable it on the netbook versions (and ubuntu has since discontinued its lpia/moblin version optimized for atom, though fedora has one).

I have a feeling atom, being an in order architecture, will benefit comparatively more from the move to x86-64 than other architectures have. While other architectures can employ register renaming to get around x86's limited set of registers, the doubling with x86-64 would greatly help atom I'd think.

 

[Gamingphreek]

Not too surprising to see some large gains with the 64 bit kernel, afaik the 32 bit kernel is compiled for the generic i686 (few optimizations and doesn't use more recent extensions), the 64 bit kernel is obviously x86-64 which includes sse2 in its minimum spec.
From the few 64 bit atom benchmarks I've seen, it gets absolutely huge performance increases with the 64 bit kernel, which makes it a real shame intel doesn't enable it on the netbook versions (and ubuntu has since discontinued its lpia/moblin version optimized for atom, though fedora has one).

I have a feeling atom, being an in order architecture, will benefit comparatively more from the move to x86-64 than other architectures have. While other architectures can employ register renaming to get around x86's limited set of registers, the doubling with x86-64 would greatly help atom I'd think.

Out of curiosity, why would the x86-64 kernel not be compiled with SSE3 as the minimum. Off the top of my head, I can't think of an x86-64 processor that doesn't have SSE3.

I would agree about the Atom processors. I am building an HTPC right now based off of Atom; however, I'm using Win7 Pro as the OS for the Media Center features (BluRay etc...). I wonder if Windows would see similar benefits on the Atom.

-Kevin

 

[Fox5]

Out of curiosity, why would the x86-64 kernel not be compiled with SSE3 as the minimum. Off the top of my head, I can't think of an x86-64 processor that doesn't have SSE3.

I would agree about the Atom processors. I am building an HTPC right now based off of Atom; however, I'm using Win7 Pro as the OS for the Media Center features (BluRay etc...). I wonder if Windows would see similar benefits on the Atom.

-Kevin

The original Opterons and Athlon 64s did not feature SSE3. Though from comments I've read, SSE3 wasn't a particularly useful stepping of SSE, the big ones were the original (just to have SIMD), SSE2 (huge improvement), and SSSE3 (extended SSE3 with the core 2's).

Windows probably would see a similar benefit, with software that's compiled for 64 bit.
IIRC, I don't think Windows Media Center is 64 bit. (and personally, I think it's a piece of crap app anyway, but unfortunately the best option for live TV and TV recording on the Windows platform, but in general PCs as Tivos will suck until cable card support comes around)

 

[Gamingphreek]

Could I not grab the latest Kernel that I want and compile with the specific options for my system to take advantage of all of that?

For instance -mtune=core2 -O3 should enable 64-bit compilation with full SS(S)E3 support.

Would it be worth it at all?

-Kevin

 

[Nothinman]

Could I not grab the latest Kernel that I want and compile with the specific options for my system to take advantage of all of that?

For instance -mtune=core2 -O3 should enable 64-bit compilation with full SS(S)E3 support.

Would it be worth it at all?

-Kevin

You could, but I doubt it would affect much. The userland apps are what really benefit from those instructions.

 

[Fallen Kell]

Windows probably would see a similar benefit, with software that's compiled for 64 bit.
IIRC, I don't think Windows Media Center is 64 bit. (and personally, I think it's a piece of crap app anyway, but unfortunately the best option for live TV and TV recording on the Windows platform, but in general PCs as Tivos will suck until cable card support comes around)

Yeah, I have to agree to an extent. I love Media Portal as a front end, but for live TV, and scheduling recordings, it sucks. I use SageTV since I got it with my tuner card a while back, and it's scheduling software is excellent, to bad it isn't nearly as flexible as Media Portal is for organizing and playing recoded shows/movies.