Re: Performance versus FreeBSD 7.0

[Nick Piggin]

On Tuesday 04 March 2008 10:23, Andi Kleen wrote:

> You're totally on the wrong path here I think.

In my testing, I found that Linux is a bit faster and more scalable
than FreeBSD on MySQL sysbench.

http://www.kernel.org/pub/linux/kernel/people/npiggin/sysbench/

I think since the mmap_sem madvise problem was solved, the kernel
didn't really have any further problems with this workload.

It is doing a lot of context switches, no IO, and not a lot of
real work. The DBMS runs into some scalability problems in this
workload, but to be fair it is probably not one that the MySQL
guys care about too much. But it sometimes seems a bit sloppy...
eg. a full 35% of the syscalls the MySQL server makes are failed
sched_setparam calls that are passing in invalid values.

So I don't really consider it a big victory to be slightly faster
here; nobody really noticed until this test that we had the silly
performance bug in our malloc/free paths in glibc and the kernel.

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