# Dual core for a desktop?

## racoontje

It looks like dual core processors will become reality soon -- Intel Pentium XE 840's or AMD's new processors, for example. Cheap x86 hardware sporting multiple cores.

My question is: is this sane practice for a desktop? I've used SMP before and I agree that it's definately the way to go if you use multithreaded programs -- database programs, video and image editing, that sort of stuff. But until mail programs go multithreading, I really don't see the benifit. You'll never be using more than one app at the same time on a normal desktop box, and the processor speed required for background tasks is hardly voluminous enough to merit multicore or SMP...

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## inode77

IMHO it's the only way @ moment to push them up because they got to the point where pushing up the frequency isn't going to work anymore.

I agree with you that normally that's not needed on a desktop system, but for us often compile/work people a nice thing to have. (Depends or wheter this was an nice excuse to get some coffee during compilation)

And remember if the market does not need what you produce, enforce/advertise that your product is needed.

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## Rad

No, I don't think it is. 'course, one can always use speedier machines to calculate some stuff that benefits from the speed. And some ppl may need to do so all the time. But for normal desktop machines -even when running Gentoo Linux-, the current "standard" models are good enough.  

And no, not even for small to midsized databases, mailservers and such. Realize that an average desktop machine can execute queries over billions of columns ("tuples") in under a second and all that stuff. And if there's a bottleneck, it's usually not the CPU...

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## lbrtuk

Just because you're running 'one app', doesn't mean you're running one process, even if it's a single threaded app. The operating system has its own threads, not to mention the fact that a user will be running a desktop environment at the same time. Being able to give a 'single threaded mail app' full reign of one processor, without it having to be preempted by any of the kernel threads or do any surplus context switches will give it a good speed up.

So with that out of the way, we're back to the old question of whether a user needs all of that speed to run a mail program. And of course the answer is no, but that won't stop them buying it and this is good for people who actually do need the speed (scientists, graphics processing people etc.) because it'll drive the price of fast equipment down to commodity levels.

Anyway, plenty of mail apps are multithreaded, even though you wouldn't think it. I'm pretty sure thunderbird has quite a lot of pthreads code in it, as does firefox.

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## racoontje

 *lbrtuk wrote:*   

> Just because you're running 'one app', doesn't mean you're running one process, even if it's a single threaded app. The operating system has its own threads, not to mention the fact that a user will be running a desktop environment at the same time. Being able to give a 'single threaded mail app' full reign of one processor, without it having to be preempted by any of the kernel threads or do any surplus context switches will give it a good speed up.
> 
> So with that out of the way, we're back to the old question of whether a user needs all of that speed to run a mail program. And of course the answer is no, but that won't stop them buying it and this is good for people who actually do need the speed (scientists, graphics processing people etc.) because it'll drive the price of fast equipment down to commodity levels.
> 
> Anyway, plenty of mail apps are multithreaded, even though you wouldn't think it. I'm pretty sure thunderbird has quite a lot of pthreads code in it, as does firefox.

 

I'm just saying if you have heavy load like something rendering a scene, you can see 90% to 95% with 2 prcoessors as opposed to one (usually it's nearer to 80 due to overhead). Gecko won't render much faster... Plus the dual core processors will be launched with a significantly lower clock speed (3.0GHz dual vs 3.8GHz single for the first Intels) so the dual core processor would be MUCH slower than the single core with higher clock speed and FSB  :Smile: 

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## lbrtuk

Probably.

Gecko itself probably wouldn't render much faster, but if you were doing heavy browsing (many tabs etc.) you'd probably see a difference. Anyway, stop, what are we talking about? We're discusing how snappy web browsing will feel on a 3GHz machine. Let's just leave it there.

As for the FSBs and frequencies, well, there's not much I can say about that. It's the cpu company's prerogative what price point they decide to aim their products at.

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## yottabit

I used to run a quad-CPU server on Gentoo. It had four 200 MHz Pentium-Pro CPUs.

Sure, 20 people could be on the system doing stuff and never notice anyone else, but run a single-threaded PHP-based Apache-served 20 GB photo database and you'll see that more CPUs isn't always king.

I now have two of these servers sitting in my basement without power.

I moved everything over to an Athlon XP 2100+ and am living the good life now:

ASUS A7N8X Deluxe board with nForce2 chipset

AMD Athlon XP 2100+

1 GB RAM

2x Hitachi 80 GB SATA drives in Linux RAID 1 (mirror) for /

2x Hitachi 250 GB SATA drives in Linux RAID 0 (stripe) for video

nForce 10/100 Ethernet built-in

D-Link Gigabit Ethernet for video array link to HTPC upstairs

Adaptec 2940UW SHA

Seagate/Certance DDS-150 20/40 GB DDS 4 mm tape backup

It's killer.

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## ikshaar

You ask for desktop, but I would say that depends if you mean home or work desktop ?

At work, I could definitively use the power of dual core, as I always have several active processes at a time. Mainly that would be a Matlab computation running in background while using my graphical interface to our database... For me the bottleneck is more the memory (I think) when I have large graphic in Matlab and I tried swicthing to another workspace. But I hope to be able to pair soon a dual core athlon 64 with a good 2-4 Gb... that will be nice  :Wink: 

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## tkdfighter

Speaking of speed, what do you need a ?ghz processor for anyways? Hell, I could check my mail on my 90mhz pentium 1 if I wanted to. But more speed is always better. You never know what you might need it for  :Cool: 

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## ikshaar

 *tkdfighter wrote:*   

> Speaking of speed, what do you need a ?ghz processor for anyways? Hell, I could check my mail on my 90mhz pentium 1 if I wanted to. But more speed is always better. You never know what you might need it for 

 

For Mom computer may be, but for me hell yes I need more, for games (!!), for computing program (Matlab)... , for compilation (for dev), etc...

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## jdgill0

You can argue for or against buying 3G machines or dual core machines when the current level of software does not match the hardware capabilities.  For one thing, having the masses of people buying the more advanced hardware helps keep the price of the hardware low.  We need the "gap" in hardware performance and software performance to allow innovation.  It's easier to innovate on an machine not being pushed to 100% of its capacity.  You can run webbrowsers on an old 486 machine no doubt, but imagine trying to develop the next generation desktop on it!  Not all people (and perhaps you can say the majority of people don't) use computers to innovate such things as the next generation desktop, but I repeat the current scheme keeps the hardware prices relatively low for everyone, allowing those who could innovate the opportunity to do so without needing to be wealthy.

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## Nuke Waste

This whole thing about "Do I really need a 50GHz quad proc desktop?" sounds a lot like "Do I really need a 64-bit desktop?" to me.  The answer is YES if a) you can afford the hardware and b) you can find the software.  As we speak, I've been using an AMD64 for a few months and FINALLY they're relasing 64-bit WinDOZE apps (which, unfortunately, I'm tied to for work).  It will take some time, but dual core will be standard.  In fact, they'll become standard in my house as soon as they're availabe!  Point is, nobody NEEDS a computer.  I find it hard to be frugal with technology when, really, if I FEEL that I NEED to use a computer for something productive, work for example, I have a machine sitting on my desk that I can use.  No, I don't think anyone NEEDS a dual core CPU to check their e-mail or even play Halo2 (http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2410) but I sure as heck WANT one!

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## moocha

 *racoontje wrote:*   

> My question is: is this sane practice for a desktop?

 YES. Trust me on that. I own a desktop SMP system, and you wouldn't believe how smooth it works even under heavy I/O load. Note that with a SMP or dual-core system you can ditch CFQ and go back to the Anticipatory I/O scheduler, yeilding wonderful results.

So (unless you're a hardcore gamer in which case you should spend more on other components, not on the CPU), dual-core is Good, Good, Good.

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## jdgill0

 *moocha wrote:*   

> ... you wouldn't believe how smooth it works even under heavy I/O load. Note that with a SMP or dual-core system you can ditch CFQ and go back to the Anticipatory I/O scheduler, yeilding wonderful results. ...

 

I do not have an SMP nor dual core system  :Sad:  ... Do you care to elaborate about the wonderful results with the Anticipatory I/O scheduler? Such information could be useful in deciding what my next upgrade would be. I also have a friend thinking of upgrading to a dual core now.

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## moocha

"wonderful results" as in "I can ditch that annoying CFQ which strangles an emerge -e world by giving I/O bandwidth priority to apps that don't really need it for reading a few files here and there, and which I can't get rid of because runtime scheduler change is a no-no for me and an updatedb makes the desktop crawl"  :Wink:  CFQ is good for a single-core desktop (although it sometimes annoys me to no end), but for a dual-core or SMP you can return to Anticipatory, which on those systems doesn't suffer from any more of its ominous latency problems.

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## jdgill0

Thanks moocha for the information.

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## R!tman

I get the idea of a program to have several threads. But how do I know if it has? lbrtuk wrote, that thunderbird is probably threaded. Ok, but I want to be sure! Or multimedia... AMD advertises that multimedia would be so much faster. Is eg. mencoder threaded? Would I be able to profit with (much) shorter encoding times? 

How many (percentage) of the programs taking a lot of cpu power are threaded? (Very small programs don't count, I don't think wget uses very much cpu)

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## tkdfighter

Check the library calls it makes. If it's threaded, it should call pthread.h. I'm not much into C yet, but that's one library I know of.

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## ikshaar

I am about to get one of these baby ... how do I make sure my kernel is dual-core friendly ? is gentoo-sources kernel already smp-enabled by default ?

Using gentoo-sources-2.6.11-r3 so far...

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## moocha

 *ikshaar wrote:*   

> how do I make sure my kernel is dual-core friendly ?

 Recompile the kernel with SMP support enabled? *ikshaar wrote:*   

> is gentoo-sources kernel already smp-enabled by default ?

 Depends on what you mean by SMP-enabled. If it's marketingomanagementspeek for "does it support SMP", then yes - any Linux kernel version has had SMP support for years.

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## R!tman

http://www.linuxhardware.org/article.pl?sid=05/05/19/1625246&mode=thread

This might be interesting. I also shows that mencoder is not smp aware  :Sad: .

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## projectle

Why not use Transcode?

What it all comes down to is, if you are even looking at using Gentoo as your OS, then GET A DAMNED DUAL CORE 64-BIT PROCESSOR!

If you are a real newb who uses your computer for solely reading e-mail, browsing the web, and the occasional word document, then you have no use for anything more than a 400MHz system with 32MB memory (all so you can play the occasional round of solitare)

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## R!tman

 *projectle wrote:*   

> GET A DAMNED DUAL CORE 64-BIT PROCESSOR!

 

You're right, for compiling the advantage is clear. Unfortunately, these CPUs are nowhere to be found, yet.

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## ikshaar

 *moocha wrote:*   

>  *ikshaar wrote:*   how do I make sure my kernel is dual-core friendly ? Recompile the kernel with SMP support enabled? *ikshaar wrote:*   is gentoo-sources kernel already smp-enabled by default ? Depends on what you mean by SMP-enabled. If it's marketingomanagementspeek for "does it support SMP", then yes - any Linux kernel version has had SMP support for years.

 

marketingomanagementspeek... well if you don't know by experience you are as guilty as them at claiming it is supported...

https://forums.gentoo.org/viewtopic-t-348062.html

Only now, support for dual-core start to be available in kernel...

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## R!tman

 *ikshaar wrote:*   

>  *moocha wrote:*    *ikshaar wrote:*   how do I make sure my kernel is dual-core friendly ? Recompile the kernel with SMP support enabled? *ikshaar wrote:*   is gentoo-sources kernel already smp-enabled by default ? Depends on what you mean by SMP-enabled. If it's marketingomanagementspeek for "does it support SMP", then yes - any Linux kernel version has had SMP support for years. 
> 
> marketingomanagementspeek... well if you don't know by experience you are as guilty as them at claiming it is supported...
> 
> https://forums.gentoo.org/viewtopic-t-348062.html
> ...

 

Hmm..., interesting. I ordered a 4400+ last week. But with the given solution on the other post, I guess there should not be a problem; I hope.

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## moocha

 *ikshaar wrote:*   

>  *moocha wrote:*    *ikshaar wrote:*   how do I make sure my kernel is dual-core friendly ? Recompile the kernel with SMP support enabled? *ikshaar wrote:*   is gentoo-sources kernel already smp-enabled by default ? Depends on what you mean by SMP-enabled. If it's marketingomanagementspeek for "does it support SMP", then yes - any Linux kernel version has had SMP support for years. 
> 
> marketingomanagementspeek... well if you don't know by experience you are as guilty as them at claiming it is supported...
> 
> https://forums.gentoo.org/viewtopic-t-348062.html
> ...

 Uh, "guilty"? Dude, take a deep breath, have some tea, relax for a while... How about stopping and thinking before jumping on people's backs like that? Geez.

Worked for me just fine with an up to date BIOS.

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## smoked

 *moocha wrote:*   

>  *racoontje wrote:*   My question is: is this sane practice for a desktop? YES. Trust me on that. I own a desktop SMP system, and you wouldn't believe how smooth it works even under heavy I/O load. Note that with a SMP or dual-core system you can ditch CFQ and go back to the Anticipatory I/O scheduler, yeilding wonderful results.

 

I can testify to this. Once upon a time I upgraded from a 450(300a overclocked) Celeron box to a box with a BP6 and two celeron 366 CPUs. As it turns out there was a reason the motherboard was so cheap. Individually the CPUs did 550 rock solid, in a dual configuration I'd get kernel warnings at anything above 366  :Sad:  That was a bummer, but here's my point:

The dual 366 box easily beat the 450 box for desktop responsiveness!

 *moocha wrote:*   

> So (unless you're a hardcore gamer in which case you should spend more on other components, not on the CPU), dual-core is Good, Good, Good.

 

I'd say you should go for dual even if you are a hardcore gamer. The most important measure of performance is the lowest FPS that you will hit when playing a game. High average is cool for brag factor, but for making sure you don't miss that important shot, the minimum is what's important. If you can manage to find benchmarks that graph framerate over time, instead of just presenting an average, I'll bet you that you'll find that the dual cores have a more even graph, with the minimum FPS substantially better than a slightly higher clocked single core CPU. I saw a benchmark some time ago that confirmed this, but of course I can't find it now.

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## ikshaar

 *moocha wrote:*   

> Worked for me just fine with an up to date BIOS.

 

You already tested an Athlon X2 ?.... on June 3 !! or are you talking about some other models ?

 *Quote:*   

> ... How about stopping and thinking before jumping on people's backs like that? Geez.

 

Funny you said that, you start mocking me for asking a fair question just few posts above... if my grammar or wording was wrong, thanks to correct me, but the sarcasm was not needed.

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## R!tman

 *ikshaar wrote:*   

>  *moocha wrote:*   Worked for me just fine with an up to date BIOS. 
> 
> You already tested an Athlon X2 ?.... on June 3 !! or are you talking about some other models ?

 

I believe there are people with these CPUs out there already. The link to the benchmark of a 4800+ on a gentoo machine is another example. There, the post was made on May 19th. 

But I think for mine to arrive another month will pass  :Sad: .

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## R!tman

After updating my bios, I plugged in my new 4400+  :Very Happy: . I am up for benchmark suggestings now!

EDIT: I never had so much fun watching firefox emerge.

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## tnt

Have you recompiled your kernel with SMP option and added MAKEOPTS="-j3" option in your /etc/make.conf ?

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## R!tman

 *tnt wrote:*   

> Have you recompiled your kernel with SMP option and added MAKEOPTS="-j3" option in your /etc/make.conf ?

 

Yes, exactly that.

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## tnt

 *R!tman wrote:*   

>  *tnt wrote:*   Have you recompiled your kernel with SMP option and added MAKEOPTS="-j3" option in your /etc/make.conf ? 
> 
> Yes, exactly that.

 

I'm sooooooooo jealous...  :Wink: 

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## ikshaar

Look ... and cry...  :Cool: 

Compilation time of mozilla-firefox-1.0.6-r2

Before upgrade (Athlon AMD64 3000+  2.0Ghz) : 46min 18sec

After upgrade (Athlon AMD64 X2 4200+  2.2GHz) : 16min 44sec

Heaven

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## tnt

 *ikshaar wrote:*   

> Look ... and cry... 
> 
> Compilation time of mozilla-firefox-1.0.6-r2
> 
> Before upgrade (Athlon AMD64 3000+  2.0Ghz) : 46min 18sec
> ...

 

Athlon64 3000+ Socket 754 Newcastle core (default 10 x 200MHz)

@ 9x275MHz ( 2475MHz ) 

single chanel NForce3 512MB Kingmax Color RAM (tiny BGA) (default 466MHz CL3 - and it's very cheap)

@ 275MHz ( 550MHz DDR) 3.0-3-3-10

Compilation time of mozilla-firefox-1.0.6-r2 in KDE (!!! - runlevel 5 - not runlevel 3 or 2)

```
real    21m15.658s

user    14m45.959s

sys     4m32.194s
```

So, try to get something better from that beast you have...  :Wink: 

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## ikshaar

Work computer = no overclocking !

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## tnt

 *ikshaar wrote:*   

> Work computer = no overclocking !

 

I'm not pushing my system to the edge - my CPU works 100% stable (38h in Prime95) at 2.55GHz with default voltage and my RAM can go up to 285MHz (570MHz DDR) stable and pass all memtest as long as you want. So, I run system lower than 2.55GHz and 570MHz to achieve 110% stability and not to have to worry at all.  :Wink: 

If I don't need CPU power (like on my file server) I test system with how low voltage it can work at default frequency.

If I don't overclock - I undervolt.  :Smile: 

You can't imagine how much reserve is left on those CPUs, and especialy on lower clock models (high frequency models like Athlon64 4000+ are already near their maximum).

Here is graph of stable states of one older Newcastle 3000+ I was able to test (it's not so good sample as mine, but it good enough):

http://www.aaen.edu.yu/~tnt/graf.png

(default factory setting is 2GHz @1.5V)

Running my 3000+ at 2.475MHz leaves me almost the same reserve like running 4000+ at stock clock.

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