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Daniel Tralamazza

Linux I/O schedulers vs workloads

This is a quick example of why one size doesn't fit all. The picture shows the TPC-C performance of MySQL under Linux running different I/O schedulers.

tpcc results

The test machine was a Dell PowerEdge R900 16-core 8 disks in RAID10.

For this kind of workloads anticiatory is expected to perform poorly (there is no idleness). I think is safe to assume that both noop and deadline are fast because the RAID controller does most of the job ordering requests. The surprise comes form CFQ terrible performance.

Source: http://www.mysqlperformanceblog.com/2009/01/30/linux-schedulers-in-tpcc-like-benchmark/

Posted by Daniel Tralamazza at 16:06
Catching disk latency in the act

Q: What happens when you scream at a bunch of disks ?

A: http://blogs.sun.com/bmc/entry/catching_disk_latency_in_the

Posted by Daniel Tralamazza at 15:21