Did you check vmstat result of each benchmarks?
Most of the problems are caused due to kernel. If you look at result
of vmstat, more than 80% CPU time are used in kernel.
It's true that heavy kernel overhead is due to Samba, and is due to
Samba generating lot's and lot's of request against kernels ( not
only disk IO, but it requires many signal handling etc ).
So, there's really two things we need to do.
1) make Linux more scalable.
( This sometimes seems as if it's tuning, but it's really bug
fix. So, don't ask performance team to tune. Let them FIX. )
2) make Samba work in less signals.
This means, don't call useless system calls, use shared memory
more effectively, divide Samba source into OS dependent part
and independent part so that you can do tuning for specific OS
and still have wide userland, etc.
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