Re: Extreme high load and low throughput using MySQL & Hybris on an HP DL380G5, quad-core Intel, 4GB RAM

[Rick James]

Thanks for the update.

One more thing to try... Turn completely off the Query Cache. Sounds strange? Well, there are some 'bugs' where the code does not play well with multi-core setups:

* InnoDB's memory allocation. (Not too bad with only 4 cores.)

* MyISAM's locks on the key_buffer.

* Query Cache contention -- This one is especially naughty because the QC is interrogated even before it realizes you should not check it. The only way to prevent the locks it to set query_cache_type = 0 (OFF); DEMAND won't do.

Also, if your CPU has HyperThreading, turn it off. HT is a CPU gimmick that works ok when the _same_ code is running in multiple cores, but degrades performance when _different_ code is running. (The HTs clobber each other's cached words.)