On Tue, 6 May 2008, Craig James wrote:
I/O Sched     AVG     Test1  Test2
---------    -----    -----  -----
cfq            705      695    715
noop           758      769    747
deadline       741      705    775
anticipatory   494      477    511

Interesting. That contrasts with some tests I did a while back on a 16-disc RAID-0, where noop, deadline, and anticipatory were all identical in performance, with cfq being significantly slower. Admittedly, the disc test was single-process, which is probably why the anticipatory behaviour didn't kick in. You are seeing a little bit of degradation with cfq - I guess it's worse the bigger the disc subsystem you have.

Matthew

--
Matthew: That's one of things about Cambridge - all the roads keep changing
         names as you walk along them, like Hills Road in particular.
Sagar:   Yes, Sidney Street is a bit like that too.
Matthew: Sidney Street *is* Hills Road.

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