On 06/06/12 19:17, Ole Tange wrote:
But if I try that setup on the test in RAM, md0_raid6 still takes up
more CPU time than the checksumming would account for.
What part of "and shunting around blocks from 20 odd block devices,
arranging them and checksumming them." are you missing?
The number your kernel gives you at bootup is to take a block of data
and checksum it. In your real world results (in the same thread as the
one doing the checksum) you are juggling the IO from all the disks,
managing the buffers that result from that and calculating all the block
positions. In what conceivable way can you conclude that a single thread
can do all that and still give you the throughput the fabricated
benchmark does?
Why not do as the man suggested and enable CONFIG_MULTICORE_RAID456 and see
what happens?
It is a lot of work to put into testing something that is at best a guess.
Can lead a horse to water.
Regards,
Brad
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