Performance Tuning

Performance Tuning

[john weber]

I've been comparing kernel compile stats online to those I get 
on my own machine, and I am baffled.

Kernel compiles take 6m38s on my P4 2.8GHz (with HT enabled) and 
512 MB RAM as compared to 20-30 seconds reported by folks online. 
I am running kernel 2.6.6.

While I understand that this varies with the config, I also don't 
see why it should vary so much.  Does anyone have any pointers on 
how I could best troubleshoot my performance?

Re: Performance Tuning

[Richard B. Johnson]

Re: Performance Tuning

[Valdis.Kletnieks]

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On Thu, 20 May 2004 12:05:15 -0000, john weber <weber@sixbit.org>  said:

> Kernel compiles take 6m38s on my P4 2.8GHz (with HT enabled) and 
> 512 MB RAM as compared to 20-30 seconds reported by folks online. 
> I am running kernel 2.6.6.
> 
> While I understand that this varies with the config, I also don't 
> see why it should vary so much.  Does anyone have any pointers on 
> how I could best troubleshoot my performance?

Step 1: Buy a machine that has 16 CPUs and 32G of memory.

Step 2: cd /usr/src/linux-2.6.6 && make -j20

Step 3: Stand back :)

Seriously - the only way to do a kernel build in 20 seconds is to use 'make
-j20' or so, and have enough processors to handle it, and enough RAM so that
you can basically do the whole thing in the fin-core cache rather than beating
on the disk....


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Re: Performance Tuning

[Prakash K. Cheemplavam]

Valdis.Kletnieks@vt.edu wrote:
> On Thu, 20 May 2004 12:05:15 -0000, john weber <weber@sixbit.org>  said:
> 
> 
>>Kernel compiles take 6m38s on my P4 2.8GHz (with HT enabled) and 
>>512 MB RAM as compared to 20-30 seconds reported by folks online. 
>>I am running kernel 2.6.6.
[snip]
> Seriously - the only way to do a kernel build in 20 seconds is to use 'make
> -j20' or so, and have enough processors to handle it, and enough RAM so that
> you can basically do the whole thing in the fin-core cache rather than beating
> on the disk....

20sec sounds very far from reality for me. I have athlon xp@2.2GHz and 
with gcc3.4 it takes about 4min to compile a 2.6.6-mm kernel. Using 
gcc3.3.x it needs minutes more.

Prakash

Re: Performance Tuning

[cliff white]

On Thu, 20 May 2004 12:05:15 +0000
john weber <weber@sixbit.org> wrote:

> I've been comparing kernel compile stats online to those I get 
> on my own machine, and I am baffled.
> 
> Kernel compiles take 6m38s on my P4 2.8GHz (with HT enabled) and 
> 512 MB RAM as compared to 20-30 seconds reported by folks online. 
> I am running kernel 2.6.6.
> 
> While I understand that this varies with the config, I also don't 
> see why it should vary so much.  Does anyone have any pointers on 
> how I could best troubleshoot my performance?

That sounds about right for your hardware. As Valdis mentioned, 20 second
compiles just don't happen on UP machines, at least not at that clock speed.
cliffw

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Re: Performance Tuning

[Tim Bird]

john weber wrote:
> I've been comparing kernel compile stats online to those I get 
> on my own machine, and I am baffled.
> 
> Kernel compiles take 6m38s on my P4 2.8GHz (with HT enabled) and 
> 512 MB RAM as compared to 20-30 seconds reported by folks online. 
> I am running kernel 2.6.6.
> 
> While I understand that this varies with the config, I also don't 
> see why it should vary so much.  Does anyone have any pointers on 
> how I could best troubleshoot my performance?

I have used compiler cache, and gotten about 30-second
compiles, after the first one, on a P4 3.0GHz.

See:  http://ccache.samba.org/

However, this isn't addressing performance of your machine, per-se.

=============================
Tim Bird
Architecture Group Co-Chair
CE Linux Forum
Senior Staff Engineer
Sony Electronics
E-mail: Tim.Bird@am.sony.com
=============================

Re: Performance Tuning

[Bill Davidsen]

john weber wrote:
> I've been comparing kernel compile stats online to those I get 
> on my own machine, and I am baffled.
> 
> Kernel compiles take 6m38s on my P4 2.8GHz (with HT enabled) and 
> 512 MB RAM as compared to 20-30 seconds reported by folks online. 
> I am running kernel 2.6.6.
> 
> While I understand that this varies with the config, I also don't 
> see why it should vary so much.  Does anyone have any pointers on 
> how I could best troubleshoot my performance?

If you are not using "make -j3" for your build you should be able to 
pick up 20-30% improvement, assuming that you have an SMP kernel running.

-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me