From mboxrd@z Thu Jan  1 00:00:00 1970
From: zhou rui <zhourui.cn@gmail.com>
Subject: same application has different performance with kernel 2.6.32/34/36
Date: Fri, 29 Apr 2011 22:46:04 +0800
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hi
my test application add a packet hook via  dev_add_pack(&prot_hook);
then copy the packet to a shared memory between userspace and kernel

tests wereperformed at same machine(DL380 G7, 12cores, intel X520 10G
nic),same traffic,same nic driver(ixgbe 3.3.9)

kernel 2.6.32.12 (SUSE SLES11,SP1)
APPlication cpu usage: 5-6%


kernel updated to  2.6.34.7
APPlication cpu usage: 19-25%

kernel 2.6.36.4 (enable/disable RPS)
APPlication cpu usage 35-40%


before I installing profile tool to find the root cause, any idea about it?
'top' result is not accurate  in older kernel? or any kernel
module/feature impact this?