Messages in this thread | | | Date | Fri, 9 Oct 2009 18:44:12 +0200 (CEST) | From | Tobias Oetiker <> | Subject | Linux IO service time - a perfect source of randomness ? |
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I have just completed extensive benchmarking of ext3 on 2.6.31.2 both on HW RAID6 as well as single Hard Drive. I have written a new file system benchmark that creates load by reading and writing large file trees in paralle to simulate a busy fileserver.
The results are as follows:
* as soon as the system comes under strain the service time for single io operations becomes almost random with huge outliers of several seconds.
* on HW RAID the best performance is to be gained with data=ordered and cfq scheduler
* on single HDD setups, only (!) data=writeback with cfq provides good performance.
* the deadline scheduler did not perform well in any of the read/write scenarios.
* btrfs has fantastic read performance but does not (yet?) do well when readers and writers are competing.
my report is on
http://insights.oetiker.ch/linux/fsopbench/
cheers tobi
-- Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland http://it.oetiker.ch tobi@oetiker.ch ++41 62 775 9902 / sb: -9900
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