Slow down across kernels

Slow down across kernels

[Phy Prabab]

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Hello,

Please cc me as I am not on this mailing list.

I have an issue with the 2.6 kernels that I am unable
to understand and correct.

I have a custom binary that I have used to compile
across different kernel versions and I am getting
vildly different numbers:
(as reported by time):

2.4.21-9  ~45s
2.4.22    ~55s
2.6.1     ~3m.40s
2.6.2     ~4m.00
2.6.3     ~4m.00
2.6.6     ~3m.15s
2.6.6-mm4 ~1m.30s

It is most shocking how much more time is spent in
user/kernel in comparsion:
2.4.21-9

5.09user 9.04system 0:43.79elapsed 32%CPU
(0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (7378946major+1139090minor)pagefaults
0swaps

VS.

2.6.6-mm4

13.06user 23.80system 1:32.00elapsed 40%CPU
(0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7537027minor)pagefaults
0swaps


The system is AMD Opteron 246 w/12G RAM and broadcom
Ge.  To rule out network issues, I have moved the
files to the local files system, ext2 on a UW320
drive.

I have also tested this on a dual Xeon 3.06GHz w/8G
RAM ge with very similar results in differences across
the kernels.

strace and make -d show no major differences.

Kernels are built with gcc323/340 and bintuils
2.13.2.1.

Could someone help me understand what is at issue
here?

Thank you and appreciate the help.
Phy





	
		
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RE: Slow down across kernels

[Phy Prabab]

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Al,

> This is unreal! 
Yep, that is why I am looking for help.

> Have you tried 2.6.5 by the way?
Yes, it was the same as 2.6.4, which was really close
to 2.6.3 or roughly 4m.

> What is it you are benchmarking if you can say?
An internal app, sorry I can not release it.  I am
trying  to figure out what is causing it and then I
can craft something neutral to submit.  Might be a day
or two to understand what is causing this issue.

Thanks!
Phy


	
		
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RE: Slow down across kernels

[Piszcz, Justin Michael]

This is unreal! 
Have you tried 2.6.5 by the way?
What is it you are benchmarking if you can say?


-----Original Message-----
From: linux-kernel-owner@vger.kernel.org
[mailto:linux-kernel-owner@vger.kernel.org] On Behalf Of Phy Prabab
Sent: Sunday, May 23, 2004 3:24 PM
To: linux-kernel@vger.kernel.org
Subject: Slow down across kernels

Hello,

Please cc me as I am not on this mailing list.

I have an issue with the 2.6 kernels that I am unable
to understand and correct.

I have a custom binary that I have used to compile
across different kernel versions and I am getting
vildly different numbers:
(as reported by time):

2.4.21-9  ~45s
2.4.22    ~55s
2.6.1     ~3m.40s
2.6.2     ~4m.00
2.6.3     ~4m.00
2.6.6     ~3m.15s
2.6.6-mm4 ~1m.30s

It is most shocking how much more time is spent in
user/kernel in comparsion:
2.4.21-9

5.09user 9.04system 0:43.79elapsed 32%CPU
(0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (7378946major+1139090minor)pagefaults
0swaps

VS.

2.6.6-mm4

13.06user 23.80system 1:32.00elapsed 40%CPU
(0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+7537027minor)pagefaults
0swaps


The system is AMD Opteron 246 w/12G RAM and broadcom
Ge.  To rule out network issues, I have moved the
files to the local files system, ext2 on a UW320
drive.

I have also tested this on a dual Xeon 3.06GHz w/8G
RAM ge with very similar results in differences across
the kernels.

strace and make -d show no major differences.

Kernels are built with gcc323/340 and bintuils
2.13.2.1.

Could someone help me understand what is at issue
here?

Thank you and appreciate the help.
Phy





	
		
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