Fedora 10 - Boot Analysis

[Eric Sandeen]

Harald Hoyer wrote:
> http://www.harald-hoyer.de/personal/blog/fedora-10-boot-analysis
> 
> A brief Fedora 10 boot analysis.
> 
> Hardware: Asus EeePC 901 with a flash disk.
> 
> Time taken from entering the encrypted root disk password until the password can 
> be entered (after pressing return in gdm). The 10 second wait in nash is ignored 
> here (which really annoys me and should be configurable in /etc/sysconfig/mkinitrd).
> 
> Default Live CD Installation:  39s (bootchart 
> http://www.harald-hoyer.de/files/f10boot/bootchart-nonread.png)
> 
> After installing readahead and running one collection boot process: 36s 
> (bootchart http://www.harald-hoyer.de/files/f10boot/bootchart-readahead.png)
> 
> At this point, I recognized that all processes (NetworkManager and newaliases), 
> which call a fsync(), let the boot process wait until all data is written to 
> disk. This is the same effect as the firefox sqlite fsync bug 
> http://shaver.off.net/diary/2008/05/25/fsyncers-and-curveballs/.
> 
> Mounting the root filessystem with relatime and turning off ordered data writing 
> for the journal with
> 
> # tune2fs -o journal_data_writeback /dev/root
> 
> improved the situation (even though data might be old on the disk after a crash, 
> but ext3 does not force the disk to empty the write cache anyway).
> 
> Turning off setroubleshoot and fixing 
> https://bugzilla.redhat.com/show_bug.cgi?id=476023 and 
> https://bugzilla.redhat.com/show_bug.cgi?id=476028: 32s (bootchart 
> http://www.harald-hoyer.de/files/f10boot/bootchart-readahead-nosetrouble.png)
> 
> Turning off bootchart: 30s
> 
> So all in all we have nearly accomplished the 30 Second Startup Feature 
> http://fedoraproject.org/wiki/Features/30SecondStartup.

Well, no; not if this requires data=writeback.  We can't ship that way,
it's a potential security hole.  You don't want someone's maildir
suddenly containing pieces of /etc/shadow or whatnot.  The old data that
may be exposed by data=writeback may not belong to that user.

-Eric