On Fri, 2003-05-16 at 11:43, Christopher Chan wrote:Hi Aryan,
can you tell us what changes you made to the elevator?
the biggest change is a patch from Andrew Morton that will give priority to reads in the presence of heavy write loads; since reads in general are things the user waits on while writes are generally asynchronous, this is a very interesting optimisation
In addition some constants used in the elevator about how agressive it can reorder have been tuned towards more interactive performance (at the cost of raw throughput/performance)
We just rebooted the mysql box in question and the vmstat 1 figures were pretty encouraging with default bdflush values.
At this time we have little traffic but we still get those big writes except that now they do not take out the reads like they used. The new elvtune numbers are very nice. =)
However, we are still going to put in those bdflush numbers we were using to spread those writes out.
Christopher
