Re: [PATCH 0/15] CFQ IO scheduler patch series

["Alan D. Brunelle" <Alan.Brunelle@hp.com>]

Using the patches posted yesterday 
(http://marc.info/?l=linux-kernel&m=117740312628325&w=2) here are some 
quick read results (as measured by iostat over a 5 minute period, taken 
in 6 second intervals) on a 4-way IA64 box with 42 disks (24 FC and 18 
U320), 42 processes (1 per disk) with 256 AIOs (16KB) outstanding at all 
times per device:

2.6.21-rc7:                                           1,006.023 MB/second
2.6.21-rc7 + new CFQ IO scheduler: 1,030.767 MB/second

showing about a 2.46% performance improvement with a 2.43% increase in 
%system used (3.738% -> 3.829%).

Interestingly enough this patch also seems to remove some noise during 
the run - see the chart at http://free.linux.hp.com/~adb/cfq/rkb_s.png

Alan D. Brunelle
HP / Open Source and Linux Organization / Scalability and Performance Group

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