[systemd-devel] systemd-udevd: excessive I/O usage

[Kok, Auke-jan H]

On Mon, Jun 4, 2012 at 3:05 PM, Peeters Simon <peeters.simon at gmail.com> wrote:
> 2012/6/4 Kok, Auke-jan H <auke-jan.h.kok at intel.com>:
>> On Mon, Jun 4, 2012 at 1:48 PM, Peeters Simon <peeters.simon at gmail.com> wrote:
>>> actually, here it is (forgotten attachment)
>>
>>
>> Could you recreate the bootchart, but this time, boot with
>> "initcall_debug=1" on the kernel commandline as well?
>>
>> This may provide some hints why your system is taking very long to
>> start doing readahead.
>>
>> You'll want to disable the bootchart collector stuff (well, all of it)
>> for the fedora bootchart package - better to uninstall it entirely.
>>
>> You might want to disable vconsole-setup if you never work on the
>> console, and don't need fancy fonts and keyboard setups on the
>> console.
>>
>> Other than that, I can see mounting takes a bit (2-3 secs) which is
>> indicative of your hard disk speed.
>
> it is just a 2.5" laptop disk, so i don't expect a lot, but the heavy
> seek, not doing much thingy bothered me
> (also, the disk gets up to 60MB/s in a straigt line)
>
>> Try removing the /.readahead file and rebooting twice before
>> generating another bootchart.
>>
>
> new bootchart after doing all the above is attached

thanks for doing that. At least now we have an idea about kernel processes.

It seems your system is taking well into 15+ seconds before btrfs is
actually *ready* on your system, which seems to be the main hiccup
(note, speculation here). I've personally become a bit displeased with
btrfs performance recently myself, so, I'm wondering if you should try
ext4 for now.

Other than that, after btrfs/udev finally pops to life, things seem to
start relatively quickly.

Auke