Possible 32-bit PAE kernel I/O slow down with 3.3.X

[Joe Ceklosky <jfceklosky@gmail.com>]

I have notice significant slow downs with disk I/O on a 32-bit PAE 3.3.X 
kernels.
The test machine has 16GB memory, Intel i5 CPU, Intel
motherboard, and an Intel 160GB SSD.  I copied 536M from one partition 
on an SSD to another.


Test 1:
kernel 3.3.2 32-bit PAE with kernel parm mem=3G

time cp -ra testdir/ /tmp
real    0m8.989s
user    0m0.094s
sys     0m1.080s


Test 2:
kernel 3.3.2 32-bit PAE

time cp -ra testdir/ /tmp
real    1m17.068s
user    0m0.173s
sys     0m2.149s


Also I tested kernel 3.2.16 32-bit PAE with no memory limits and it
was in line with test 1.

Am I doing something wrong or could something have been broken in PAE 
with kernel 3.3.X?



Thanks,
Joe Ceklosky

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