Re: Choosing and tuning Linux file systems

[Valerie Henson <val_henson@linux.intel.com>]

On Mon, Jun 26, 2006 at 02:04:17AM -0700, Nate Diller wrote:
> 
> heh, in other words, "bring on the flames, FUD, death threats, etc"

Shhh!!!  Sh!!!  Someone might hear you! :)

Seriously, I used to be a file system absolutist.  Then I talked to
people who actually used file systems to do work.  They had this
irritating habit of saying things like, "I have requirement XYZ for my
workload, and only fs ABC can do that."  And I would think, "Well,
you're right.  You do have to use that fs for your workload."  So I'm
focusing on the boundary conditions - when do you absolutely want to
use a particular file system and not another?

> you might also want to mention ext3 reservations, they can definitely
> increase performance for streaming workloads, and can be increased by
> changing a #define.  too bad this sort of thing isn't generalized for
> all the FS's, with some sort of pre-allocation/mapping addition to the
> aops.  it could even replace the bmap() call.

Recently I was writing up an article on transparent large page support
and realized how much large page reservations and disk block
reservations had in common.  I highly recommend reading this paper,
"Practical, Transparent Operating System Support for Superpages," by
Juan Navarro, et al.:

http://www.cs.rice.edu/~ssiyer/r/superpages/

Or if you either have a LWN subscription or can wait until Wednesday
when it becomes free, my summary of the paper:

http://lwn.net/Articles/187921/

Especially the population maps and the lists of reservations of
particular sizes look interesting.

-VAL