PAE bug in 2.4?!

[Ilya <khext@mail.ru>]

Hi,

I've ASUS P4P800-Mx-EAYVZ motherboard and have to use a 2GB memory. But
after including PAE support in kernel it almost twice... Surely, i
understand, that it's inevitable, the slowing of PAE, but twice?! Does
anybody faced this problem? Or is there some bug in PAE?! I tested the
PAE at some other motherboards, but only on this model on asus it works
strange) 

Best rgds, Ilya

Below, you can find some usefull info about this situation.

Cpu info:
khext@al:~$ cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 2
model name      : Intel(R) Celeron(R) CPU 2.40GHz
stepping        : 9
cpu MHz         : 2400.156
cache size      : 128 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 2
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid
bogomips        : 4784.12

Here is the difference in kernels:
khext@al:~$ diff linux-2.4.31/.config linux-2.4.31-PAE/.config
61,62c61,62
< CONFIG_NOHIGHMEM=y
< # CONFIG_HIGHMEM4G is not set
---
> # CONFIG_NOHIGHMEM is not set
> CONFIG_HIGHMEM4G=y
64c64,65
< # CONFIG_HIGHMEM is not set
---
> CONFIG_HIGHMEM=y
> CONFIG_HIGHIO=y

Here is my test:
khext@al:~$ cat pl
for ($j=1;$j<5;$j++){
$num=250000*$j;
$a="";
for ($i=0; $i<$num/72; $i++) {
        $a.='1234567890qwertyuiopasdfghjklzxcvbnm';
        $a.='1234567890QWERTYUIOPASDFGHJKLZXCVBNM';
}
printf ("len=".length($a)."\n");
$b="";
$k=345345342;
for ($i=0; $i<1000000; $i++) {
        $k*=34523;
        $k%=$num;
        $k=abs($k);
        $b.=substr(substr($a, $k, 4097),$k%4097,1);
}
printf ("b=".length($b)."\n");
printf (substr($b, 10, 5)."\n");
}

Test themselfs...
With PAE turned on:

khext@al:~$ uname -a
Linux al 2.4.31 #25 SMP Wed Nov 2 19:05:47 MSK 2005 i686 GNU/Linux
khext@al:~$ free
             total       used       free     shared    buffers
cached
Mem:       2059812      30656    2029156          0       2512
9744
-/+ buffers/cache:      18400    2041412
Swap:      4883720          0    4883720
khext@al:~$ time perl pl
len=250056
b=991920
xPnx7
len=500040
b=996000
SqnSb
len=750024
b=997280
e2ux7
len=1000008
b=997960
SLuSb

real    0m33.436s
user    0m33.210s
sys     0m0.220s

With PAE turned off:
khext@al:~$ uname -a
Linux al 2.4.31 #25 SMP Wed Nov 2 19:00:05 MSK 2005 i686 GNU/Linux
khext@al:~$ free
             total       used       free     shared    buffers
cached
Mem:        903880      27640     876240          0       2492
9756
-/+ buffers/cache:      15392     888488
Swap:      4883720          0    4883720

khext@al:~$ time perl pl
len=250056
b=991920
xPnx7
len=500040
b=996000
SqnSb
len=750024
b=997280
e2ux7
len=1000008
b=997960
SLuSb

real    0m17.208s
user    0m16.780s
sys     0m0.430s

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