RAID performance / tuning?

[Tiago Freire]

Dear LKML,

I am a long-time linux user, but not a C dev.
I have been using software RAID since I had an Athlon 64 3000, which
at the time took a toll of up to 30% of the CPU time on big writes (4
200GB disks on RAID 5), if my memory serves me well.
If you can get me some clarifications, I would be incredibly grateful.
Shouldn't software RAID always surpass hardware, given fast enough hardware?
Why is it that software RAID on current systems still gets less
performance than hardware counterparts?
Also, are there any knobs/pulleys/ledgers in the linux kernel so that
I can maximize RAID operation performance?
Given that our current bottleneck is the disk IO, it would take a
sincere effort to saturate the CPU with raid/disk operations (you'd
need lots and lots of disks).

Best regards
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