[systemd-devel] [PATCH] readahead: read /usr files last for rotational media, skip /var

[Stephan Kulow]

Am Freitag, 30. September 2011, 16:52:01 schrieb Tom Gundersen:
> On Fri, Sep 30, 2011 at 4:26 PM, Paolo Bonzini <bonzini at gnu.org> wrote:
> > On 09/30/2011 03:39 PM, Kay Sievers wrote:
> >> Sure. I just think that this is not what we really want in the end.
> > 
> > That I agree with, but good is the enemy of perfect...
> 
> How about this:
> 
> Rather than making the split between / and /usr, make it between
> Before and After basic.target (as basic.target is roughly what
> traditionally would require files to be on /). This would require us
> to associate files to be readahead with services, but based on what
> you wrote in a previous message that should be easy enough.
> 
That's what we achieved with SUSE's preload - through systemtap
we got all relevant syscalls to later determine a process tree and
IO done by what service. This way we could later readahead only
the files of a given service before starting it.

It made a huge difference, but it was also pretty complex and fragile.

Greetings, Stephan