On Wed, Mar 6, 2013 at 8:17 PM, Greg Smith <g...@2ndquadrant.com> wrote: > TL;DR summary: on a system I thought was a fair middle of the road server, > pgbench tests are averaging about a 2% increase in WAL writes and a 2% > slowdown when I turn on checksums. There are a small number of troublesome > cases where that overhead rises to closer to 20%, an upper limit that's > shown up in a few tests aiming to stress this feature now.
I have only done some cursory research, but cpu-time of 20% seem to expected for InnoDB's CRC computation[0]. Although a galling number, this comparison with other systems may be a way to see how much of that overhead is avoidable or just the price of entry. It's unclear how this 20% cpu-time compares to your above whole-system results, but it's enough to suggest that nothing comes for (nearly) free. [0]: http://mysqlha.blogspot.com/2009/05/innodb-checksum-performance.html -- fdr -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
