MySQL config [WAS: ]uilding a new workstation - dual or quad-core CPU for FreeBSD 7?

Philip M. Gollucci philip at ridecharge.com
Tue Sep 18 08:34:21 PDT 2007


Philip M. Gollucci wrote:
>>> my.cnf
>>> innodb_thread_concurrency = 8
>> You want '0' or performance will suck.  There's a basic architectural
>> flaw in how mysql handles non-zero concurrency values here (innodb
>> accesses are serialized by a global mutex that protects a counter to
>> check if it should try to allow more innodb concurrency.  Duh.)
>>
>> Anyway, assuming your disks can keep up you should see a big performance
>> boost when you switch to 7.0.  This is a fairly big "if" though: I don't
>> know if it's even feasible for a write-heavy database to saturate 8 CPUs
>> instead of being bottlenecked by disk speeds and leaving the CPUs mostly
from /usr/local/share/my-innodb-heavy-4G.cnf

# This permits the application to give the threads system a hint for the
# desired number of threads that should be run at the same time.  This
# value only makes sense on systems that support the
# thread_concurrency()
# function call (Sun Solaris, for example).
# You should try [number of CPUs]*(2..4) for thread_concurrency
thread_concurrency = 8

# Number of IO threads to use for async IO operations. This value is
# hardcoded to 4 on Unix, but on Windows disk I/O may benefit from a
# larger number.
innodb_file_io_threads = 4

# Number of threads allowed inside the InnoDB kernel. The optimal value
# depends highly on the application, hardware as well as the OS
# scheduler properties. A too high value may lead to thread thrashing.
innodb_thread_concurrency = 16


Apparently its only set in this file.

We should probably submit a bug to MySQL rather then add a patch to
ports or do both and remove the ports when its released.


-- 
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Philip M. Gollucci (philip at ridecharge.com) c:323.219.4708 o:703.749.9295x206
Senior System Admin - Riderway, Inc.
http://riderway.com / http://ridecharge.com
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