32bit vs 64bit vs 32bit-PAE

English Open Chat
#1

Hello All,

I am just curious … who uses a 64bit os … and more interesting … why?

The question is not intended for the “I run a mega-monster-database” crowd. I know why yall like the extra bits … see below … :slight_smile:

I’m interested in the personal workstation.

Background:

Going back to the early 90’s, it is very easy to see the appeal of mainstream applications capable of addressing 32bits of memory. It’s NOT difficult to hit the 16bit address space limit using something like Lotus 1-2-3 or Microsoft’s Excel. I remember this happening to many non-geek colleagues.

32bit addresses 4GB of memory. This trivial piece of information almost answers the “why?”. If you run an application that requires/likes more than 4GB memory (hello again mega-monster-database folk) … bingo! I’d love to know what commonly used applications are so greedy, assuming there are such apps.

For the use case scenario of many apps in a 32bit environment, PAE allows the kernel to work with up to 64GB of memory, so that multiple memory-hungry 32bit apps can run side by side. Is there a distinct advantage of native 64bit for this use case? Is there a common perception of a native 64bit advantage here?

My final question: any folk who can’t like without 64bit emacs?

CHEERS

#2

Well OK.

I’m on 11.2 64bit. The only reason I chose 64 bit is because my processor is a 64 bit processor (AMD Turion x64). Its a 64 bit procesor, so I went for a 64 bit OS :slight_smile:

Laptop’s got 2G of RAM in it, so 32bit would work equally well.
I do surfing the internets and “web developing” (overused term that one) on it so nothing grandiose :slight_smile:

I did check berforehand (asking on forums & general gogling about) whether or not the 64 bit problems (I’m looking at you, Flash) had been sorted out before I went for it.
Actually, Flash has now gone backwards so I have heard. But thats its own problem, not mine.

So: Because I can is my answer

#3

I run both, for the sake of being able to help those that do decide to need to use 32 bit.
But would use _64 by choice as it’s supremely supported in Linux generally, particularly so in openSUSE

#4

64 bit comes handy in two things I do; first I run a lot of VMs, usually concurrently and they easily chomp 6-10GB of memory from the system (I’m currently sporting 16) and the other thing is, multimedia handling on a native 64 bit system is way, way faster - especially things like transcoding and video manipulation.

If you run a server and don’t run 64, you should be spanked because the performance difference is just… a lot.

#5

On Mon, 2010-08-16 at 14:36 +0000, oxala wrote:
> Hello All,
>
> I am just curious … who uses a 64bit os … and more interesting
> … why?

Well… there’s the common answers like performance and memory.
Certainly one could argue that 32bits is fine if less than 4G (esp less
than 3.5G usable).

But, my own experience NOW is that 64bits is important for future
FEATURES. For example, virtualization options will require CPU features
and we’re seeing a lot of push to 64bit. Granted, running a hypervisor
on top of an OS is passe… and perhaps it will not be a restriction
there but only for bare metal hypervisors in which case the point it
moot.

>
> The question is not intended for the “I run a mega-monster-database”
> crowd. I know why yall like the extra bits … see below … :slight_smile:
>
> I’m interested in the personal workstation.

Actually, you’re interested in a low end personal desktop and NOT a
workstation. The workstation moniker carries a higher end usage with
it. So, we’ll assume large memory there.

There are lots of things that will continue to require more and more
memory and just like 256M was plenty for your “workstation” not too many
years ago, 4G will seem equally as small in the near future.

>
> Background:
>
> Going back to the early 90’s, it is very easy to see the appeal of
> mainstream applications capable of addressing 32bits of memory. It’s
> NOT difficult to hit the 16bit address space limit using something like
> Lotus 1-2-3 or Microsoft’s Excel. I remember this happening to many
> non-geek colleagues.
>
> 32bit addresses 4GB of memory. This trivial piece of information
> almost answers the “why?”. If you run an application that
> requires/likes more than 4GB memory (hello again mega-monster-database
> folk) … bingo! I’d love to know what commonly used applications are
> so greedy, assuming there are such apps.

Lots of things are cached… including the filesystem. Having more
memory can mean a huge performance increase in the areas of shared
filesystems in particular. So… even if you just run a couple of
apps… you might see some real benefit if you happen to run shared
filesystems as well.

>
> For the use case scenario of many apps in a 32bit environment, PAE
> allows the kernel to work with up to 64GB of memory, so that multiple
> memory-hungry 32bit apps can run side by side. Is there a distinct
> advantage of native 64bit for this use case? Is there a common
> perception of a native 64bit advantage here?

PAE does NOT allow you to violate the 2G limit on individual processes
(a limit that is there because of 32bit). So… while it’s nice to say
that PAE saves the day… it’s really only useful if running a lot
processes.

>
> My final question: any folk who can’t like without 64bit emacs?

Excellent point… when editing files, old vi was simply not good enough
because it assumed how big of a file could be handled and it was quickly
surpassed. Moving forward, the idea of bringing up a 2G+ file is
certainly not out of the question… so 64bits could be useful there as
well.

#6

Hello,

I run a lot of VMs, usually concurrently and they easily chomp 6-10GB of memory from the system

I expected this answer from at least one person here. To my mind, virtualization is the most compeling reason for 64bit, aside from any application specific use cases (e.g. big rdms).

multimedia handling on a native 64 bit system is way, way faster - especially things like transcoding and video manipulation.

I “THINK” I have seen some benchmarks supporting this point; it’s certainly an interesting area. There “may” be an intrinsic advantage for these types of operations deriving from larger word size. Most video files of any duration are HUGE, so the ability to easily manipulate memory in excess of 4GB may provide an advantage here, especially for applications that implement “non-linear video editing” features.

the performance difference [of 64bit] is just… a lot.

This is a common misconception, that 64bit is intrinsically faster than 32bit. It is also a misconception that has some basis in reality for those of us on intel/amd. All else being equal, a 64bit implementation of any software (os included) is likely to be slower than a 32bit implementation. Each word sent to the cpu must be 64bits long, whether it needs to be or not. Of course the magical caveat of economists and geeks like me, “all else being equal”, never holds in reality. When AMD developed the 64bit extensions to the i386 ABA, they improved one of the most limiting factors of the i386 archetecture, the pausity of registers. Running an intel/amd processor in 64bit mode, more registers are available than running the same cpu in 32bit mode. Ars Technica published several excellent articles touching this subject in thier “CPU Theory and Praxis” section some years back. I apologize; I’m unable to find the links to the specific articles I had in mind. Additionally, Tom’s Hardware is real treasure trove of benchmarks for anyone who happens to be interested in killing some time.

As to whether or not the performance of a server can be characterized as generally “better/faster/rounder/squarer” on 64bit versus 32bit on intel … I don’t know, but I am certainly skeptical. With the exception of large rdbms backends, I have never ran an application on a server that needed/wanted more than 4GB of ram. It’s easy to forget just how “HUGE” 4GB or memory address space really is …

CHEERS!

#7

I suggest you Google for Apache benchmarks 32-vs-64 for starters as well as MySQL performance, cluster performance etc. The net is full of example where 64bit servers completely destroy the 32bit variants and you don’t have to feel “skeptical” about it.

And it has nothing to do with how much memory the system has or doesn’t have.

#8

Hello cjcox,

Thanks for sharing your thoughts with me.

Actually, you’re interested in a low end personal desktop and NOT a
workstation. The workstation moniker carries a higher end usage with
it. So, we’ll assume large memory there.

Perhaps this point belongs in a different thread altogether, but nonetheless, I find it difficult to differentiate the “workstation” from the “low end desktop” these days. Spend $70 on an add on graphics card from NVidia or ATI … and that old Octane box looks really old … and still very cool :D!

I offer a couple of observations:

  1. Some of the most compute instensive aspects of the “personal” computer are in the “personal” part. GUI/EyeCandy/3D-Desktop/Wysiwyg/oooh how pretty/And how many colors does that come in?/ …

  2. Tasks metioned elsewhere in this thread, such as non-linear video editing, are being peformed by folk like my mom!

while it’s nice to say that PAE saves the day… it’s really only useful if running a lot processes

Yep! So the implicit question is wheter or not the apps we commonly run on our “workstations/low end desktops” really benifit for the extra memory address space?

As a comical or ironic account of my own experience … the 2 gig of memory I’m using today actually serve me better than they did a few years back due to efficiency imporvements in the gnome enviroment and some of the apps I use … including VMWare, Bibble Pro, Inckscape, … I just get happier and happier computing at the low end!

And gnome + compiz + cairo-dock looks and runs great on my <$300 netbook …

CHEERS!

#9

As a comical or ironic account of my own experience … the 2 gig of memory I’m using today actually serve me better than they did a few years back due to efficiency imporvements in the gnome enviroment and some of the apps I use … including VMWare, Bibble Pro, Inckscape, … I just get happier and happier computing at the low end!

I’m inclined to agree with that

#10

On Mon, 2010-08-16 at 18:06 +0000, oxala wrote:
…
> > while it’s nice to say that PAE saves the day… it’s really only useful
> > if running a lot processes
>
> Yep! So the implicit question is wheter or not the apps we commonly
> run on our “workstations/low end desktops” really benifit for the extra
> memory address space?

Very good point… this is why 32bit netbooks are still very useful…
and… for some even that is too much and a “smart” phone does the
trick.

>
> As a comical or ironic account of my own experience … the 2 gig of
> memory I’m using today actually serve me better than they did a few
> years back due to efficiency imporvements in the gnome enviroment and
> some of the apps I use … including VMWare, Bibble Pro, Inckscape, …
> I just get happier and happier computing at the low end!
>
> And gnome + compiz + cairo-dock looks and runs great on my <$300
> netbook …
>
> CHEERS!

Again, the kicker of me is when certain advanced features are NOT there
unless you move to 64bit… otherwise, I think your point is well
taken.

#11

On Mon, 2010-08-16 at 17:36 +0000, Chrysantine wrote:
> oxala;2207199 Wrote:
> > As to whether or not the performance of a server can be characterized as
> > generally “better/faster/rounder/squarer” on 64bit versus 32bit on
> > intel … I don’t know, but I am certainly skeptical.
> I suggest you Google for Apache benchmarks 32-vs-64 for starters as
> well as MySQL performance, cluster performance etc. The net is full of
> example where 64bit servers completely destroy the 32bit variants and
> you don’t have to feel “skeptical” about it.
>
> And it has nothing to do with how much memory the system has or doesn’t
> have.

yes… I agree here… this is part of the features that come with
running a 64bit OS with a 64 bit capable processor. So… while most
(light user) might not see a tremendous boost, it is there nonetheless.

#12

Yes, provided that you are aware that Apache gives the largest uplift in performance and so figures for Apache will be flattering with respect to anything else, that is an interesting thing to do.

as well as MySQL performance, cluster performance etc. The net is full of example where 64bit servers completely destroy the 32bit variants and you don’t have to feel “skeptical” about it.

And there are quite a few where it doesn’t. Try this phoronix benchmark ([Phoronix] Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks](http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1)) for some examples of both the Apache effect and of the opposite…although it does suffer from the usual Phoronix problem of insufficient detail about the set-up.

Note also that there is a ‘hardware dependency’; the earlier Intel Core2Duo platform didn’t have the virtualisation acceleration instructions in 64 bit, but did in 32 bit (and what sense did that make, Intel?), so you had a bit of an unfortunate choice. Have the virtualisation acceleration instructions and don’t have the larger memory support that you need or have the support for the memory and don’t have the virtualisation acceleration. AMD didn’t push virtualisation users into this unfortunate dilemma.

#13

Hello again cjcox,

You wrote:

the kicker of me is when certain advanced features are NOT there
unless you move to 64bit…

I don’t fully understand this statement. I am unaware of any amd and/or intel features that would be available only when the processor is in 64bit mode. I can only infer that you mean features in the oses themselves. If you could elaborate a little, it would certainly be appreciated.

Thanks!

#14

It makes me wonder how many people care about taking full advantage of all of their RAM, while don’t care about using the full capabilities of their CPU. AMD64 is more than just wider address registers.

#15

Not quite true, pae-kernels support up to 4GiB of RAM per process (and 64GiB in total).

#16

On 2010-08-17 16:36, BuddelBob wrote:
>
> It makes me wonder how many people care about taking full advantage of
> all of their RAM,

I can use my 8 GiB in 32 bits, ie, all my ram.

About the cpu capabilities: I have tested video conversion both in 32 and 64 bits, and… I didn’t
notice any difference. The only test that did a difference was a dd with a block size of 4GiB.

Yes, I’, using 64 bit oS - no real reason why. Just in case. Because I can. Because it will be the
future. Because, in theory, some apps could run faster.

There is no speed difference. It just means that the cpu can move more data in the same time - which
can mean a programs can do such things faster if the memory can cope with that load, but it also can
mean much larger (double) footprints if programmers made a mistake.

–
Cheers / Saludos,

Carlos E. R.
(from 11.2 x86_64 “Emerald” GM (Elessar))

#17

On 2010-08-17 17:36, gropiuskalle wrote:
>
> “cjcox” Wrote:
>> PAE does NOT allow you to violate the 2G limit on individual processes
>> (a limit that is there because of 32bit). So… while it’s nice to say
>> that PAE saves the day… it’s really only useful if running a lot
>> processes.
>
> Not quite true, pae-kernels support up to 4GiB of RAM per process
> (and 64GiB in total).

Yes and no :slight_smile:

The limit per process is 4 GiB, yes. But the kernel has to use some of that space, and some for
paging… so the useful space per process is lower. I think it is 3.5, can’t confirm.

–
Cheers / Saludos,

Carlos E. R.
(from 11.2 x86_64 “Emerald” GM (Elessar))

#18

I did some testing on this a couple of months ago, had a 32 and 64 bit install on the same disk, same machine, 8 GB of RAM. I did get a difference in video conversion, quite some difference to be honest. On 32 bit, conversion of a DVD9 to DVD5 took 11 minutes, on 64 bit the same action took 8 minutes. Same difference for conversion of a .dv file to mpeg.
And, like Chrysantine wrote, read the benchmarks for Apache. Or try to find articles proving that 32bit outblows 64bit…

I’ve been running 64bit linux ever since I’ve had 64bit machines. Yeah, flash, but that’s due to some company’s policy.

#19

Knurpht wrote:

>
> I did some testing on this a couple of months ago, had a 32 and 64 bit
> install on the same disk, same machine, 8 GB of RAM. I did get a
> difference in video conversion, quite some difference to be honest. On
> 32 bit, conversion of a DVD9 to DVD5 took 11 minutes, on 64 bit the
> same action took 8 minutes. Same difference for conversion of a .dv
> file to mpeg.
> And, like Chrysantine wrote, read the benchmarks for Apache. Or try to
> find articles proving that 32bit outblows 64bit…

It only takes the right combination of hardware and requirements. I run
openSUSE 32bit on a number of AMD64 boxes, all with 1Gb RAM - I get
more processes to fit in the RAM in 32bit than I do in 64bit mode.

–
Per Jessen, Zürich (18.8°C)
http://en.opensuse.org/User:pjessen

#20

On 2010-08-18 12:06, Knurpht wrote:
>
> I did some testing on this a couple of months ago, had a 32 and 64 bit
> install on the same disk, same machine, 8 GB of RAM. I did get a
> difference in video conversion, quite some difference to be honest. On
> 32 bit, conversion of a DVD9 to DVD5 took 11 minutes, on 64 bit the same
> action took 8 minutes. Same difference for conversion of a .dv file to
> mpeg.

It will depend on the particular codecs you use. In my case, the difference was minimal. Hey, one of
the conversions is actually slower if told to use the 4 cores: it runs faster on one core. Which
means, I instead convert four different videos at the same time.

> And, like Chrysantine wrote, read the benchmarks for Apache. Or try to
> find articles proving that 32bit outblows 64bit…

I’m not saying that 32 bits is faster, either :slight_smile:

See my sig below :wink:

> I’ve been running 64bit linux ever since I’ve had 64bit machines. Yeah,
> flash, but that’s due to some company’s policy.

Yeah, but it happens.

–
Cheers / Saludos,

Carlos E. R.
(from 11.2 x86_64 “Emerald” GM (Elessar))