speed up Firefox start by a factor of 3 on x86

[William John Murray]

On Fri, 2006-03-17 at 01:14 -0500, fedora-test-list-request at redhat.com
wrote:
> The Firefox browser often takes 15 seconds to start because random
> placement
> of the vDSO page disrupts the pre-linking of the 133 shared libraries
> involved.
> (Fedora Core 5 Test 3, kernel-2.6.15-1.2054_FC5, updated by yum to
> today,
> 1.1GHz Athlon Plain, 768MB RAM, ext3 UDMA100 local disk.)  Similar
> delays
> are encountered by any application that uses many or large shared
> libraries.
> 
> In contrast, Firefox always starts in 5 seconds or less on a kernel
> which places
> the vDSO intelligently: just below the .text of ld-linux or the main
> executable.
> This preserves the benefits of exec-shield (including randomization,
> when prelink
> randomizes) without destroying performance.
> 
> Want to experience the difference for yourself?  These two kernels
> have
> only my patch applied on top of what will be released Monday as Fedora
> Core 5:
>   (14MB)
> http://bitwagon.com/ftp/kernel-2.6.15-1.2054_FC5.jreiser.i686.rpm
> 
  I don't see much here. I get 8-10s to start firefox the first time
after boot, 2-3s after that (2GHz Centrino, 1Gb ram, ext3 sata disk)
with either kernel. For oodraw it is 13s first time, 3s subsequently.

 Immediately after running prelink the first-start time drop maybe 20%,
but reboot and that disappears.
   I don't see any significant improvement...
           Bill