On Fri, 15 Mar 2002, Peter Zaitsev wrote: > 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
> For Next test I'll try to use Ingo's scheduler to see if it helps to > solve the problem, also I'll try to test real mysql server to see > which slowdown it will have. I think it would be instructive to try using NGPT and either a patched kernel or 2.4.19-pre3 which has the extra system calls included. I make no predictions, but large improvements have been noted with a large number of threads. > > > > > CODE: (Dumb one just for test) > > > #include <stdio.h> > #include <pthread.h> > #include <time.h> > #define NUM_TH 1000 You might want to read this from the command line as an option and malloc the vecors. Just a thought, I'm bad at guessing how lare a test I may want to run. -- bill davidsen <[EMAIL PROTECTED]> CTO, TMR Associates, Inc Doing interesting things with little computers since 1979. --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
