Re: IDE performance drop between 2.4.23 and 2.6.0

[Jean-Luc Fontaine <jfontain@free.fr>]

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I solved the problem in a very strange way. Note that the (b) disk
performance only improves after readahead has been increased on another
(c) drive! (the (c) drive performance was also increased by to 2.4
levels but is not shown here). I could reliably repeat this behavior
after rebooting.

Can any IDE expert explain it?

# hdparm /dev/hdb
~ multcount    =  0 (off)
~ IO_support   =  1 (32-bit)
~ unmaskirq    =  1 (on)
~ using_dma    =  1 (on)
~ keepsettings =  0 (off)
~ readonly     =  0 (off)
~ readahead    = 256 (on)
~ geometry     = 65535/16/63, sectors = 80418240, start = 0
# hdparm -t /dev/hdb
~ Timing buffered disk reads:   34 MB in  3.09 seconds =  11.02 MB/sec
# hdparm -a 4096 /dev/hdb
/dev/hdb: readahead = 4096 (on)
# hdparm -t /dev/hdb
~ Timing buffered disk reads:   34 MB in  3.08 seconds =  11.04 MB/sec
# hdparm -a 4096 /dev/hdc
/dev/hdc: readahead = 4096 (on)
# hdparm -t /dev/hdb
~ Timing buffered disk reads:   46 MB in  3.12 seconds =  14.76 MB/sec



- --
Jean-Luc Fontaine  mailto:jfontain@free.fr  http://jfontain.free.fr/
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