OSDL tiobench Sequential Reads improved with AS due to read-aheadchanges

[Judith Lebzelter]

Hello;

I have compiled the results for tiobench with Anticipatory Scheduler for
before and after the addition of the readahead-revert-lazy-readahead patch
in the 2.6.1-mm4 kernel.   I have found our SCSI systems showed up to 50%
improvement in Sequential Reads on ext2.  (2-CPU/MegaRAID/RAID0/5disks and
4-CPU/AACRAID/RAID0/5disks).  Here are the plots:

http://developer.osdl.org/judith/tiobench/big_jump_SR_24CPU/sr.html

Oddly, random reads also show slight improvement:

http://developer.osdl.org/judith/tiobench/big_jump_SR_24CPU/rr.html

Our 2CPU/MegaRAID particularly has been underperforming in the past, but
now is much more comparable to 'deadline'.  Here are plots of the current
-mm and mailine kernels:

http://developer.osdl.org/judith/tiobench/2CPU_big_jump_SR/sr.html

Thanks;

Judith Lebzelter
OSDL



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