[kwlug-disc] [Phoronix] Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks

[unsolicited]

Another aspect of interest in this sort of thing, as I asked in the 
past on this list is - for today's < 4 GB hardware, e.g. netbooks, are 
there pros/cons to 32/64 going forward.

I tried XP64 at one point and quickly tossed it - all my current (32 
bit) programs required (a) re-installation (after conversion) - I had 
to go find 64-bit setup.exe's, and (b) didn't run. Eff that.

So, I was concerned and asked here if there were any issues of that 
nature in Linux, going forward.

John came back and indicated the 64-bit installs came with, or 
dependencies caused, 32-bit (<thunk>?) libraries to come down, keeping 
everything happy.

So, my conclusion were, and I'd sure like to hear if they're wrong: 
(a) over time 64-bit will take over (be the norm / no 32-bit 
workarounds), even on these small machines, (b) 32-bit will continue 
to work and there's no harm, and no real user-perceivable significant 
performance degradation to running 64-bit on these < 4 GB machines 
that can't really use the 64-bit.

If these perceptions are wrong, do please pipe up.

Chris Irwin wrote, On 12/31/2009 10:22 AM:
> On Thu, Dec 31, 2009 at 04:45, Lori Paniak <ldpaniak at fourpisolutions.com 
> <mailto:ldpaniak at fourpisolutions.com>> wrote:
> 
>     A while back, someone was asking about the performance differential
>     between 32-bit and 64-bit kernels.  Here is some data for ubuntu karmic:
> 
>     http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1
>     <http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1>
> 
>     Short version:  Not much difference unless you are serving web pages,
>     doing SSL or disk I/O.  For those cases, 64-bit may be an order of
>     magnitude faster.
> 
> There was a lot of discussion in their forum thread associated with this 
> article. There are all sorts of variables that people wanted expressed 
> in the article.
> 
> 1. He was using Ubuntu, so it was i386 vs modern AMD64. So how much of 
> this was affected by having things like SSE, etc. There was a request to 
> try using an i686-targetted system (such as Arch). There was also a 
> request to use gentoo and actually build the system with the same 
> capabilities for 32- and 64-bits, but I doubt anybody wants to spend two 
> weeks doing that ;)
> 
> 2. There was an question regarding userspace. Would a 64-bit kernel 
> booting the stock 32-bit system provide a speed improvement? I would 
> lean toward 'no', as I think most of the improvements were the userspace 
> utilities being able to take advantage of all the extra registers and 
> capabilities of the 64-bit platform. I'm not that knowledgeable about 
> hardware specifications, so it's just a gut feeling.
> 
> So basically, he framed it as 32-bit vs 64-bit, which at the high level 
> ("which iso do I download?") is correct. But below that it may be that 
> some of these improvements may be possible in 32-bit if said 32-bit 
> system targeted modern hardware capabilities, which is the more pressing 
> question considering the audience of that site (They're generally 
> curious in Hows and Whys).
> 
> Also, not to nitpick (though I do so love playing the part), but your 
> short summary read like "64-bit isn't worth it except in these specific 
> instances". I read the article as coming more across as "There are no 
> regressions, but you may get improved performance in specific 
> instances". Subtle difference, but it would affect whether somebody 
> decided to install a 32- or 64-bit system.
> 
> Although it did make me somewhat curious. I use ecryptfs for my home 
> directory, and am curious about 32-vs-64 comparisons for that (in light 
> of the SSL test in the article).