Peter Zaitsev writes:
> Hello mysql,
>
> Some time ago I wrote about slow down of mysql with large number of
> threads, which is quite common in Linux-Apache-Mysql-PHP enviroment.
>
> The test was simulating the worst case of concurrency - all the
> threads are modified global variable in a loop 5000000 times in
> total, using standard mutex for synchronization. The yeild is used
> in a loop to force even more fair distribution of lock usage by
> threads and increase context switches, therefore it did not change
> much with large number of threads. I.e with 64 threads time without
> yeild is 1:33.5
>
> Test was run on PIII-500 1G RAM Kernel 2.4.18. 3 runs were made for
> each number of threads and best results were taken:
>
> Num threads. Time Peak cs rate.
> 2 53.4 179518
> 4 53.8 144828
> 16 1:06.3 85172
> 64 1:48.1 48394
> 256 8:10.6 10235
> 1000 36:46.2 2602
>
I hope you are using latest glibc 2.2 with our patches applied.
Also please try adaptive mutex. How to set it, take a look at
mysys/my_thr_init.c.
--
Regards,
__ ___ ___ ____ __
/ |/ /_ __/ __/ __ \/ / Mr. Sinisa Milivojevic <[EMAIL PROTECTED]>
/ /|_/ / // /\ \/ /_/ / /__ MySQL AB, Fulltime Developer
/_/ /_/\_, /___/\___\_\___/ Larnaca, Cyprus
<___/ www.mysql.com
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