KernelTrap: Reworking Readahead

“Steven Pratt posted a request for comments to the lkml
regarding a patch to simplify the readahead logic in the 2.6 Linux
kernel. With the patch he offered some benchmark test results which
he summarized by saying, “the new code was always equal to or
better than the current code on all variation and all test
configurations.” Regarding the goal of the patch, he explains:

“‘The key design point of the new design is to make the
readahead code aware of the size of the I/O request. This change
eliminates the need for treating large random I/O as sequential and
all of the averaging code that exists just to support this…'”

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