Re: How is random_page_cost=4 ok?

Greg Smith wrote:

> The drives themselves, and possibly the OS and disk controller, are all
> running read-ahead algorithms to accelerate this case. In fact, this
> *exact* case for the Linux read-ahead stuff that just went mainline
> recently: http://kerneltrap.org/node/6642

Apparently only the "simple" stuff hit mainline, see [1] and [2], not
knowing how this turns out for pg-style loads, especially compared to
the full-fledged patch.

Readahead is probably too much of a beast that no one dares to touch
with a 3-foot-pole, unless given a large team with good standing in the
kernel community and concerted regression testing in whatever
environment Linux is used these days...

michael

[1] http://lwn.net/Articles/235164/
[2]
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=history;f=mm/readahead.c