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Re: Fedora 10 - Boot Analysis



On Mon, 2008-12-15 at 15:47 +0100, 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), 

Odd, NM isn't intentionally calling fsync() (it's not anywhere in the
code), nor does glib do that anywhere that I can find.  I can't think of
anything that would require an fsync for NM, so I'm interested in
finding this and killing it.

dan

> 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.
> 
> To reach the 20 Second Startup Feature 
> http://fedoraproject.org/wiki/Features/20SecondStartup, we really have to tackle 
> setroubleshootd. Also we might start to move basic services to upstart and start 
> them in parallel (bootchart with some services moved 
> http://www.harald-hoyer.de/files/f10boot/bootchart-readahead-nosetrouble-upstart.png). 
> Parallel booting will show now benefits with readahead and a small amount of 
> active services, but the more services are turned on, the more you benefit with 
> a parallel boot setup. Moving more basic modules to be compiled in the kernel 
> also would gain some seconds. Speaking about modules, I ported Jakubs modprobe 
> patch to the recent 3.6pre1 module-init-tools version. Though it nearly halves 
> I/O, it would only safe us a fraction of a second here (not recognizable).
> 
> In the end, we also have to extend our view to things that happen after the user 
> logs in (bootchart http://www.harald-hoyer.de/files/f10boot/bootchart-full.png) 
> and do an extended analysis. Work is also in progress by Gnome developer Behdad 
> Esfahbod http://mces.blogspot.com/2008/12/improving-login-time-part-3.html.
> 


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