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TL_CLD 12-28-2006 10:41 AM

Slackware 11 and shiny new dual core CPU's
 
I'm in the process of building a new server that'll be running Apache with some fairly heavy PHP stuff. This is not the first server I'm building using Slackware, but it is the first where I'm considering going for one of those fancy new dual core CPU thingies.

But what's that I hear? I need a "special" SMP enabled kernel?

I've never done anything remotely kernel related, as I've never really had the need. Before I started using Slackware (September 2006) kernel upgrading was done automatically by the patcher (swup in my case) if I opted for it. With Slackware I've just decided to run with whatever kernel Pat V. decided was best for Slackware to ship with.

This has done me good so far.

But what if I want to take advantage of this new dual core CPU? Will I need to do anything specific when installing, and if so, are there any pitfalls I should be aware of?

Perhaps someone could point me in the right direction, preferably to something really beginner-friendly, as messing with the kernel actually scares me a bit. :)

And finally will I even see any significant performance gains from SMP on a server running only Apache/PHP, because if it's a matter of a "measly" 10-15%, then I'd rather avoid the whole issue and just go with the fastest single core CPU I can find.. hehe

Sincerely,
Thomas

tuxrules 12-28-2006 12:48 PM

Quote:

Originally Posted by TL_CLD
But what's that I hear? I need a "special" SMP enabled kernel?

Yes you would need "SMP-Aware" kernel to actually take advantage of both core. But using a non-smp kernel on a smp machine will not damage your machine in any way. It will just use one core.

You can get SMP support either by using Pat's precompiled kernel with SMP support or by compiling your own kernel. Look into /extra in the slackware repo for Pat's precompiled version. You can always take that kernel config file as your base and remove the modules/support for things you don't use/need.

Quote:

But what if I want to take advantage of this new dual core CPU? Will I need to do anything specific when installing, and if so, are there any pitfalls I should be aware of?
Pitfalls??? not that I can think of. I am running AMD dual-core myself but as a desktop. As far as I say, I haven't had a single problem.

Quote:

Perhaps someone could point me in the right direction, preferably to something really beginner-friendly, as messing with the kernel actually scares me a bit. :)
It is actually not that difficult. I was skeptical too when I first started with slackware but now I always compile my own kernels. I started out with the digital hermit howto and it worked out pretty well for me.

Quote:

And finally will I even see any significant performance gains from SMP on a server running only Apache/PHP, because if it's a matter of a "measly" 10-15%, then I'd rather avoid the whole issue and just go with the fastest single core CPU I can find.. hehe
Well, the performance gains heavily depend on the traffic. If your site would be a low traffic personal website, you can easily use a single-core with enough ram. I too run a personal website with low traffic (single core Intel 1.8 GHz, 768MB RAM). As far as I can say, I am only limited by my upstream connection (running from home DSL).

I guess more experienced LQers would throw some more light on this specific question.

Tux,

TL_CLD 12-28-2006 02:03 PM

tuxrules: Yes indeed you do.. :)

I've read the link you provided, and while I don't understand it all, I did walk away feeling fairly confident that this is something I can handle.

I've also found some other resources here and there, and from what I gather, I should be able to modify my existing config to include SMP support, and then just compile the kernel with that. Is that correct?

I'm running 2.4 (the stock kernel in Slackware 11). How does that kernel handle itself in a SMP enviroment?

Regards,
Thomas

tuxrules 12-28-2006 02:28 PM

Quote:

Originally Posted by TL_CLD
I've also found some other resources here and there, and from what I gather, I should be able to modify my existing config to include SMP support, and then just compile the kernel with that. Is that correct?

Yes you can absolutely recompile a 2.4 series kernel to just include SMP support. I actually haven't compiled a 2.4 series kernel so I can't comment on the process/complexities but it includes few more steps as compared to a 2.6 series compile. BTW, I run 2.6 series even on the server.
Quote:

I'm running 2.4 (the stock kernel in Slackware 11). How does that kernel handle itself in a SMP enviroment?
Again, I have little idea since I have never used 2.4 in SMP environment. As I said, I use dual-core machine as a desktop so 2.6 series kernel makes more sense (at least to me) on a desktop.

Tux,

davidsrsb 12-29-2006 03:06 AM

2.4 SMP has rather crude locking and is much less efficient than the 2.6 SMP code.
I have a new dual core coming next week and will be installing 2.6 on it.

TL_CLD 12-29-2006 03:45 AM

http://www-128.ibm.com/developerwork...brary/l-web26/

It really does seem like 2.6 is the way to go when doing webservers with Apache. :)

Thomas

davidsrsb 12-29-2006 04:30 AM

I would not install 2.4 on a new machine as too many recent chipsets are not supported. 2.4 is in bugfix/maintenance mode for some time now.

nemestrinus 01-01-2007 11:21 PM

Yes, I also wanted to run a dual-core (pentium D) processor and in the end I wound up compiling and installing a fresh linux-2.6.19.1 from kernel.org, because no prior kernels would support all the chipsets that were on my abit motherboard. Everything seems to work fine so far! The only hard part turned out to be getting the .config file exactly as I needed it.

TL_CLD 01-02-2007 02:02 AM

I've successfully compiled a SMP enabled 2.4.34 kernel, and I'm pretty proud! :)

Next up I'm going to try it with a 2.6 kernel, as I've read many good things about 2.6 and SMP.

Thanks for all the help guys.

Thomas


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