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

[Paolo Bonzini]

On 09/30/2011 04:52 PM, Tom Gundersen wrote:
> 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.

It's actually pretty hard unless you give up the ability to 
replay/collect at the same time, which I think would be really bad.  The 
problem is that replay will read files for "after basic.target" long 
before that target has completed, and this will fool collect.

Pretty hard means perhaps just a couple days of work---not much, but 
orders of magnitude more than this patch not counting the time needed to 
review it etc.

I can even "promise" I'll do it sooner or later, but better readahead 
would be a nice feature for F16 which will still have the /usr split. :)

Paolo