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Re: readahead_early.



On Fri, Oct 05, 2007 at 04:02:21PM -0400, Dave Jones wrote:
> Right now we're running readahead early way too late.
> At a time when we've just sat doing no IO at all for 10
> seconds whilst (amongst other things) we waited for a
> DHCP lease.   We're also running it at a time when
> we're competing for disk bandwidth with other processes.
> The result is that disabling the service completely shows
> no change in boot time at all.
> http://www.codemonkey.org.uk/junk/bootchart-before.png
> 
> Moving the readahead_early service to start really early
> wins back 4 seconds of boot up time.
> http://www.codemonkey.org.uk/junk/bootchart-after.png

 Please, define "really early".

 I have (workstation, F7, 2GB RAM):

   - /etc/rc5.d/S01readahead_early

   - /etc/readahead.d/custom.early
     (generated by readahead-collector from F8)

   - only one readahaed list 
     (merged .early and .later lists)

 results (readahead on/off):

 http://people.redhat.com/kzak/readahead/f7-on.png
 http://people.redhat.com/kzak/readahead/f7-off.png

 .. so nothing useful :-(

> Any reason not to change this for F8 ?

 I don't believe that readahead is able to really improve Fedora boot
 time.

    Karel

-- 
 Karel Zak  <kzak redhat com>


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