2.6 kernel series have noticeable performance regression

[yangyi <yang.yi@bmrtech.com>]

Hi, All

I did a performance regression test for all the 2.6 kernel series on two
x86 platforms in last two weeks and found that some version kernels do
have noticeable performance regression, some performance indices have
about 20 to 30 percent regression,
 even several indices have over 30 percent fall.

For example, on Toshiba tecra8000 laptop: for 4-bytes packet, network
throughput of 2.6.11 is just about 57.5 percent of 2.6.0, for pipe
bandwidth, the value of 2.6.11 is just about 68 percent of that value of
2.6.0, for mmap latency, the value of 2.6.11 is about 1.8 times as long
as 2.6.0.

On supermicro-6012-p6, for 64-bytes small packet, network throughput of
2.6.11 is about 66.72 percent of 2.6.0, for 0K-size 2 processes context
switch time, 2.6.11 is 31.8 percent bigger than 2.6.0, for pipe latency,
2.6.10 is 35.85 percent bigger than 2.6.3.

So, I think that it is very very necessary to find the problems and fix
them ASAP.

The following articles give out all the test results, the article "2.6
kernel series have noticeable performance regression, part 1" gives out
the test results on SuperMicro-6012-p6, the article "2.6 kernel series
have noticeable performance regression, part 2" gives out the test
results on Toshiba tecra8000 laptop.