Slow queries on 4.0.13, FreeBSD 4.8 STABLE, linuxthreads, zawodny blog

[LS]

On my FreeBSD 4.8 machine running 4.0.13 with linuxthreads, I am seeing the
symptoms described in Jeremy's blog here
(http://jeremy.zawodny.com/blog/archives/000203.html):

2. Unfair Scheduling

We've seen instances when a single MySQL thread doing a lot of I/O work (deleting a
lot of rows from a table) seems to monopolize all the CPU time. When this happens,
even the most trivial SELECT queries against unrelated tables can take a long time
or even block until the heavy I/O work is complete. It feels like somehow the I/O
thread is unfairly getting more of the CPU time.

But compiling with linuxthreads is said to offer fair scheduling:

LinuxThreads on FreeBSD
The most popular solution is to recompile MySQL and link it with the LinuxThreads
library. Doing so gives you the benefits of kernel assisted "threading" (fair
scheduling, SMP, and not needing thread-safe gethostbyname()).


The server is handling 800qps, and the slow query log is showing hundreds of cases
where trivial unrelated INSERT DELAYED queries are being held up for 2 seconds. Is
there something else I need to do to get these slow queries to go away?

Thanks!


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