Messages in this thread | | | From | Roger Larsson <> | Subject | Re: Very High Load, kernel 2.4.18, apache/mysql | Date | Wed, 25 Sep 2002 23:26:10 +0200 |
| |
The big question is - why that much CPU usage?
Possible answers: * PHP, mySQL, Apache - needs that amount of CPU to perform the requested function. (you have got suggestions from others)
* The implementation if either has bugs that cause the CPU usage. Garbage collection? Ineffective algorithms? - Not much to do other than collecting execution profiles, quite advanced - recompiling of the tools will probably be needed... And probably help from the tools developers...
* The implementation of the user code has bugs that cause the CPU usage. One example: SQL SELECT with unindexed data - this can usually be noticed as buffer in load in vmstat but since all data fits in memory - it would cause scans in memory, with lots of RAM cache misses... And it would work well as long as the scanned data was smaller than the CPU cache? - Suggestion: Review your index keys and select statements to make sure that they match!
/RogerL - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |