[arch-general] Think twice before moving to systemd

[Felipe Contreras]

On Fri, Aug 17, 2012 at 6:22 AM, Denis A. Altoé Falqueto
<denisfalqueto at gmail.com> wrote:
> On Thu, Aug 16, 2012 at 5:54 PM, Felipe Contreras
> <felipe.contreras at gmail.com> wrote:
>> On Thu, Aug 16, 2012 at 4:08 PM, John K Pate <j.k.pate at sms.ed.ac.uk> wrote:
>>> On Thu, 16 Aug 2012 15:16:31 +0200
>>> Felipe Contreras <felipe.contreras at gmail.com> wrote:
>>>
>>>> On Wed, Aug 15, 2012 at 7:58 PM, Denis A. Altoé Falqueto
>>>> <denisfalqueto at gmail.com> wrote:
>>>> > This is so stupid that it's not even funny. You said that the problem
>>>> > was having CONFIG_HZ=300 and systemd. I said it is not, because I also
>>>> > have that situation and it works. So, your point is moot. I didn't say
>>>> > you don't have a problem, but just that it may be not related to
>>>> > CONFIG_HZ. I even sent you an article with ways on how to inspect the
>>>> > behaviour of systemd, which was completely ignored.
>>>>
>>>> My problem with CONFIG_HZ exists
>>>> independently of whether you experience the problem yourself or not.
>>>
>>> But it suggests that the problem is not *just* systemd and
>>> CONFIG_HZ=300. I am, and many others are, running systemd with
>>> CONFIG_HZ=300 fine.
>>
>> Show me two bootcharts, one with CONFIG_HZ_300=y, and another with
>> CONFIG_HZ_1000=y. Then I will believe that you are running systemd
>> fine. The other possibility is that you are just not noticing the
>> problem.
>
> Chalange accepted.
>
> http://dl.dropbox.com/u/9222479/bootchart-arch-hz300.png
>
> Bootchart of 20 seconds, with Arch stock kernel, CONFIG_HZ=300. You
> can see that kdm is started in around 7 seconds after boot starts.
>
> http://dl.dropbox.com/u/9222479/bootchart-ck-hz1000.png
>
> Same length chart, with CK patchset kernel, from AUR package (some
> problems compiling stock kernel with CONFIG_HZ=1000, not related to
> systemd at all0. You'll be amazed to see kdm starting at around the
> same time.

Funny that you say "around the same time", when it's clearly less than
6 seconds, so it's 15% slower, but that's the second instance of kdm.
The first instance starts at 2s in 1000 hz, and 4s in 300 hz, so
there's *clearly* a big difference.

Perhaps the boot of KDE is so slow that in comparison the difference
is small and you don't notice the issue, but I certainly notice a
*huge* difference with SLiM and Xfce.

And still, you should be using the same kernel for a fair comparison,
not 3.4.8 vs 3.5.2 + patches. You can certainly use 3.5.2 + patches
for both.

Cheers.

-- 
Felipe Contreras