>-----Original Message----- >From: OKAN ARI [mailto:okan...@aribem.com] >Sent: Monday, July 06, 2009 10:54 AM >To: mysql@lists.mysql.com >Subject: Dramatic performance problem > >Hi to every body, I am newbie for mysql lists. I have a mysql server >with 2GB of ram and Core2Duo cpu. Until today mysql server had very >acceptable performance results. But today, server is very slow. No db >change, no php code change. But I can't find the reason of this >slowness. > >I am using MYSQL PERFORMANCE TUNING PRIMER -- - By: Matthew >Montgomery - to set up my.cnf and some results are below > >(Results are taken from script but server is up only 2 hours) > >TABLE CACHE >Current table_cache value = 2060 tables (THIS VAS 512 I HAVE INCREASED) >You have a total of 204 tables >You have 771 open tables. >The table_cache value seems to be fine > >MAX CONNECTIONS >Current max_connections = 500 >Current threads_connected = 9 >Historic max_used_connections = 232 >The number of used connections is 46% of the configured maximum. >Your max_connections variable seems to be fine. > > >MEMORY USAGE >Max Memory Ever Allocated : 1 G >Configured Max Per-thread Buffers : 2 G >Configured Max Global Buffers : 554 M >Configured Max Memory Limit : 2 G >Physical Memory : 1.96 G >Max memory limit exceeds 90% of physical memory > > >How can I define the problem of performance?
[JS] Without really knowing what is going on, and without having paid much attention to tuning MySQL, I would suspect that you have run out of memory somewhere inside MySQL. Even though you've configured a max memory limit of 2GB, it is possible that various other parameters are limiting the actual memory limit to the 1GB shown in your memory usage report. When you run out of CPU, performance degrades more or less gradually (up to perhaps 80% or 90%). The same is true of disk bandwidth. Running out of memory, on the other hand, is like hitting a brick wall: either you have enough, or you don't. From there on you are pinning your hopes on the intelligence of the memory management techniques being used. Once the system begins thrashing, things will spiral out of control. Memory swapping will drive the disks to their limit, and you might mistake it for a disk bottleneck. This is based solely on my former life as a performance consultant. Oh, and remember this sad truth: there is **always** a bottleneck in a system. ;<)= > >Best Regards, >OKAN -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql?unsub=arch...@jab.org
