Tech Blog » cache http://informationideas.com/news Using technology to help your business Thu, 05 Aug 2010 22:53:22 +0000 en hourly 1 http://wordpress.org/?v=3.0.1 Mysql SQL_NO_CACHE Benchmark Problem http://informationideas.com/news/2008/02/25/mysql-sql_no_cache-benchmark-problem/ http://informationideas.com/news/2008/02/25/mysql-sql_no_cache-benchmark-problem/#comments Mon, 25 Feb 2008 23:57:00 +0000 frank http://informationideas.com/news/2008/02/25/mysql-sql_no_cache-benchmark-problem/ I have been trying to benchmark the sql calls to mysql from an application without success. Even when I set the SELECT statement to SQL_NO_CACHE, the results seemed to be still cached. Apparently, Linux does its own caching of disk reads also. That was giving me incorrect benchmark results if I hit the same data twice.

For those using Linux kernel 2.6.16 or higher, you can clear Linux cache with the following command.
echo 3 > /proc/sys/vm/drop_caches

Unfortunately for me, I am stuck on 2.5.xx and will have to figure out another method.

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