> something simple and easily fixable. Linux kernel is not multithreaded and this
> mean that when kernel doing work (say flushing MySQL data on disk) userlevel
> process can not interrupt it. Work is going to improve situation (important
Thats not correct. When disk I/O is being queued other userspace tasks run
whenever the I/O blocks. So mysql will generate a lot of I/O and spend most
of its time asleep where other stuff can run. Of course all the other stuff
probably wants the disk too.
At that point with heavy I/O the SMP scaling issues you mention kick in on
2.2 as does the elevator algorithm flaw where we are starving some processes
excessively under high I/O load.
Alan
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