Re: slow down in 2.6 vs 2.4

[Phy Prabab]

Oh, there is an important bit of information missing,
the test is compiling gcc-3.4.0 using gcc-3.2.3 with
binutils-2.13.2.1.  The machine used is a dual 2.8GHz
Xeon w/8G RAM (no ht).

config line is --enable-languages=c,c++
--prefix=/usr/tmp/foo

BTW, the unit never swaps when building.

Thanks!
Phy

--- Con Kolivas <kernel@xxxxxxxxxxx> wrote:
> 
> Hi Phy
> 
> You said:
> Over the last two days I have been struggling with
> understanding why 2.6.x kernel is slower than
> 2.4.21/23 kernels.  I think I have a test case which
> demostrates this issue.
> make times:
> 
> 2.4.21:
> 323.68user 56.07system 6:35.77elapsed 95%CPU
> (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs
> (3138783major+3818347minor)pagefaults
> 0swaps
> 
> 2.6.7-rc3-s63 (SPA scheduler):
> 334.01user 69.86system 7:01.47elapsed 95%CPU
> (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (13301major+6931745minor)pagefaults
> 0swaps
> 
> 2.6.7-rc3:
> 336.17user 68.41system 7:02.47elapsed 95%CPU
> (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (13301major+6931745minor)pagefaults
> 0swaps
> 
> 
> ----
> Your 2.4 compile is showing a massive number of
> major page faults. Just how big
> is this compile you do? Can you try running the 2.6
> compile with 
> 
> echo 100 > /proc/sys/vm/swappiness
> 
> Con
> 


	
		
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