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Old 08-15-2012, 01:35 AM
Felipe Contreras
 
Default Think twice before moving to systemd

Hi,

I just became aware that Arch Linux plans to switch to systemd, and
this worries me for several reasons.

I tried systemd a while ago in a brand new machine with Arch Linux and
the boot was *much slower*. After some exchanges with Lennart
Poettering and other people in Google+[1], it became clear I was on my
own. Eventually I found the culprit: Fedora uses CONFIG_HZ_1000, and
Arch Linux uses CONFIG_HZ_300. It became clear to me that systemd was
not ready for prime time, it wasn't thoroughly tested in a lot of
machines, and if you have problems Lennart Poettering will blame you
(PulseAudio sounds familiar?).

systemd was the reason I stopped using Fedora in the first place; when
they moved to it my machine stopped booting reliably. My configuration
was non-standard (a single encrypted partition), so I guess they never
tested that. Similarly, I expect many Arch Linux users to bite these
corner-cases.

Finally, it's much harder to debug. If you have a problem you will not
be able to open a script and figure out what is happening, and perhaps
modify it, and debug it. You would be greeted with an unmodified
binary, and the source code would be along these lines:

http://cgit.freedesktop.org/systemd/systemd/tree/src/remount-fs/remount-fs.c

I'm sure in due time systemd will be ready, and will have nice
advantages, but I doubt that's the case right now. Has anybody looked
into the CONFIG_HZ issue? I doubt that.

I was expecting more from the Arch Linux community, something along
the lines of Google's analysis to pick to mercurial[2], but so far I
have only seen a couple of people saying +1 in the development mailing
list, with barely any explanation at all. Such an important move (one
that might make users' machines stop booting) should warrant at least
an analysis of some sort, with clear advantages. Would it not?

At the moment I am unconvinced; does systemd has any *real* advantage?
I don't think so; the potential of breakage outweighs the "supposed"
advantages, and I think a proper analysis would show that.

Cheers.

[1] https://plus.google.com/108736516888538655285/posts/BTG39o6YoGS
[2] http://code.google.com/p/support/wiki/DVCSAnalysis

--
Felipe Contreras
 
Old 08-15-2012, 01:42 AM
Brandon Watkins
 
Default Think twice before moving to systemd

On Tue, Aug 14, 2012 at 9:35 PM, Felipe Contreras <
felipe.contreras@gmail.com> wrote:

> Hi,
>
> I just became aware that Arch Linux plans to switch to systemd, and
> this worries me for several reasons.
>
> I tried systemd a while ago in a brand new machine with Arch Linux and
> the boot was *much slower*. After some exchanges with Lennart
> Poettering and other people in Google+[1], it became clear I was on my
> own. Eventually I found the culprit: Fedora uses CONFIG_HZ_1000, and
> Arch Linux uses CONFIG_HZ_300. It became clear to me that systemd was
> not ready for prime time, it wasn't thoroughly tested in a lot of
> machines, and if you have problems Lennart Poettering will blame you
> (PulseAudio sounds familiar?).
>
> systemd was the reason I stopped using Fedora in the first place; when
> they moved to it my machine stopped booting reliably. My configuration
> was non-standard (a single encrypted partition), so I guess they never
> tested that. Similarly, I expect many Arch Linux users to bite these
> corner-cases.
>
> Finally, it's much harder to debug. If you have a problem you will not
> be able to open a script and figure out what is happening, and perhaps
> modify it, and debug it. You would be greeted with an unmodified
> binary, and the source code would be along these lines:
>
>
> http://cgit.freedesktop.org/systemd/systemd/tree/src/remount-fs/remount-fs.c
>
> I'm sure in due time systemd will be ready, and will have nice
> advantages, but I doubt that's the case right now. Has anybody looked
> into the CONFIG_HZ issue? I doubt that.
>
> I was expecting more from the Arch Linux community, something along
> the lines of Google's analysis to pick to mercurial[2], but so far I
> have only seen a couple of people saying +1 in the development mailing
> list, with barely any explanation at all. Such an important move (one
> that might make users' machines stop booting) should warrant at least
> an analysis of some sort, with clear advantages. Would it not?
>
> At the moment I am unconvinced; does systemd has any *real* advantage?
> I don't think so; the potential of breakage outweighs the "supposed"
> advantages, and I think a proper analysis would show that.
>
> Cheers.
>
> [1] https://plus.google.com/108736516888538655285/posts/BTG39o6YoGS
> [2] http://code.google.com/p/support/wiki/DVCSAnalysis
>
> --
> Felipe Contreras
>
I haven't had this issue at all, and so far the systemd developers have
been very accommodating to the arch developers
 
Old 08-15-2012, 01:51 AM
Jason Ryan
 
Default Think twice before moving to systemd

On 15/08/12 at 03:35am, Felipe Contreras wrote:
> Hi,
>
> I just became aware that Arch Linux plans to switch to systemd, and
> this worries me for several reasons.
>
> snip

I am running it on both my home machines and my work laptop. I have full
encryption on all three devices and LVM and Raid1 on two of them. Boot time is
not considerably faster, but shutdown is.

I have not had any problems migrating or running the three machines in the
intervening fortnight.

I think your concerns are largely unfounded and your alarmist tone does no
credit to the Arch developers who have given this some consideration and have
implemented it in a typically thorough and professional manner.

/J


--

http://jasonwryan.com/ [GnuPG Key: B1BD4E40]
 
Old 08-15-2012, 02:01 AM
Felipe Contreras
 
Default Think twice before moving to systemd

On Wed, Aug 15, 2012 at 3:51 AM, Jason Ryan <jasonwryan@gmail.com> wrote:
> On 15/08/12 at 03:35am, Felipe Contreras wrote:

>> I just became aware that Arch Linux plans to switch to systemd, and
>> this worries me for several reasons.
>>
>> snip
>
> I am running it on both my home machines and my work laptop. I have full
> encryption on all three devices and LVM and Raid1 on two of them. Boot time is
> not considerably faster, but shutdown is.
>
> I have not had any problems migrating or running the three machines in the
> intervening fortnight.

So you have 3 data-points. There's plenty of different machines and
configurations out there, and the way you present your arguments seems
to suggest that because you didn't have any problems, that proves that
nobody out there can *possibly* have issues with systemd.

I believe the opposite; even if you have tested in one thousand
machines, the *possibility* still remains.

> I think your concerns are largely unfounded and your alarmist tone does no
> credit to the Arch developers who have given this some consideration and have
> implemented it in a typically thorough and professional manner.

I tend to not believe things without evidence, and not believe because
of some "authority" says it's true. I will believe there was some
careful analysis, when I see the result of the analysis in a
summarized form as the Google DVCS analysis. If the benefits are well
known, and the disadvantages minded, it shouldn't be difficult to
write such a summary. Would it?

Cheers.

--
Felipe Contreras
 
Old 08-15-2012, 02:40 AM
Jason Ryan
 
Default Think twice before moving to systemd

On 15/08/12 at 04:01am, Felipe Contreras wrote:
> On Wed, Aug 15, 2012 at 3:51 AM, Jason Ryan <jasonwryan@gmail.com> wrote:
> > On 15/08/12 at 03:35am, Felipe Contreras wrote:
>
> >> I just became aware that Arch Linux plans to switch to systemd, and
> >> this worries me for several reasons.
> >>
> >> snip
> >
> > I am running it on both my home machines and my work laptop. I have full
> > encryption on all three devices and LVM and Raid1 on two of them. Boot time is
> > not considerably faster, but shutdown is.
> >
> > I have not had any problems migrating or running the three machines in the
> > intervening fortnight.
>
> So you have 3 data-points. There's plenty of different machines and
> configurations out there, and the way you present your arguments seems
> to suggest that because you didn't have any problems, that proves that
> nobody out there can *possibly* have issues with systemd.
>
No - I made no such overarching claims; I just countered your experience with my
own.

> I believe the opposite; even if you have tested in one thousand
> machines, the *possibility* still remains.

Yes, the possibility exists; that is hardly a reason to spread FUD on the list
though, is it?

> > I think your concerns are largely unfounded and your alarmist tone does no
> > credit to the Arch developers who have given this some consideration and have
> > implemented it in a typically thorough and professional manner.
>
> I tend to not believe things without evidence, and not believe because
> of some "authority" says it's true. I will believe there was some
> careful analysis, when I see the result of the analysis in a
> summarized form as the Google DVCS analysis. If the benefits are well
> known, and the disadvantages minded, it shouldn't be difficult to
> write such a summary. Would it?
>
I look forward to your analysis (which by your own criteria will need to include
> 1000 machines, presumably); or are you expecting someone else will do this
to satisfy your demands for scientific rigour?

/J

--

http://jasonwryan.com/ [GnuPG Key: B1BD4E40]
 
Old 08-15-2012, 03:17 AM
Denis A. Altoé Falqueto
 
Default Think twice before moving to systemd

On Tue, Aug 14, 2012 at 10:35 PM, Felipe Contreras
<felipe.contreras@gmail.com> wrote:
> Hi,
>
> I'm sure in due time systemd will be ready, and will have nice
> advantages, but I doubt that's the case right now. Has anybody looked
> into the CONFIG_HZ issue? I doubt that.

Arch's stock kernel:

$ zgrep CONFIG_HZ /proc/config.gz
# CONFIG_HZ_100 is not set
# CONFIG_HZ_250 is not set
CONFIG_HZ_300=y
# CONFIG_HZ_1000 is not set
CONFIG_HZ=300

Systemd is working fine enough. A counter example shoud invalidate
your argument that CONFIG_HZ is the culprit.

--
A: Because it obfuscates the reading.
Q: Why is top posting so bad?
For more information, please read: http://idallen.com/topposting.html

-------------------------------------------
Denis A. Altoe Falqueto
Linux user #524555
-------------------------------------------
 
Old 08-15-2012, 03:45 AM
Denis A. Altoé Falqueto
 
Default Think twice before moving to systemd

On Wed, Aug 15, 2012 at 12:17 AM, Denis A. Altoé Falqueto
<denisfalqueto@gmail.com> wrote:
> On Tue, Aug 14, 2012 at 10:35 PM, Felipe Contreras
> <felipe.contreras@gmail.com> wrote:
>> Hi,
>>
>> I'm sure in due time systemd will be ready, and will have nice
>> advantages, but I doubt that's the case right now. Has anybody looked
>> into the CONFIG_HZ issue? I doubt that.
>
> Arch's stock kernel:
>
> $ zgrep CONFIG_HZ /proc/config.gz
> # CONFIG_HZ_100 is not set
> # CONFIG_HZ_250 is not set
> CONFIG_HZ_300=y
> # CONFIG_HZ_1000 is not set
> CONFIG_HZ=300
>
> Systemd is working fine enough. A counter example shoud invalidate
> your argument that CONFIG_HZ is the culprit.


This can also really help you debug your problem:

http://0pointer.de/blog/projects/self-documented-boot.html

--
A: Because it obfuscates the reading.
Q: Why is top posting so bad?
For more information, please read: http://idallen.com/topposting.html

-------------------------------------------
Denis A. Altoe Falqueto
Linux user #524555
-------------------------------------------
 
Old 08-15-2012, 04:33 AM
Leon Feng
 
Default Think twice before moving to systemd

2012/8/15 Felipe Contreras <felipe.contreras@gmail.com>:
> Hi,
>
> Finally, it's much harder to debug. If you have a problem you will not
> be able to open a script and figure out what is happening, and perhaps
> modify it, and debug it. You would be greeted with an unmodified
> binary, and the source code would be along these lines:
>
> http://cgit.freedesktop.org/systemd/systemd/tree/src/remount-fs/remount-fs.c
>

The fact is you do not need to debug these scripts anymore. One
foo.service is tested ok in one distro, it will be push into upstream
and all other distro can just use it.

When blame the C file here, do not forget most of the program you use
is using C. The problem with bash script is they can not be
used/shared between different distro. So every distro has to maintain
their own script. It is a waste of time and resources.

Leon

> Cheers.
>
> [1] https://plus.google.com/108736516888538655285/posts/BTG39o6YoGS
> [2] http://code.google.com/p/support/wiki/DVCSAnalysis
>
> --
> Felipe Contreras
 
Old 08-15-2012, 05:35 AM
Tom Gundersen
 
Default Think twice before moving to systemd

Felipe,

On Aug 15, 2012 3:35 AM, "Felipe Contreras" <felipe.contreras@gmail.com>
wrote:
> I tried systemd a while ago in a brand new machine with Arch Linux and
> the boot was *much slower*. After some exchanges with Lennart
> Poettering and other people in Google+[1], it became clear I was on my
> own. Eventually I found the culprit: Fedora uses CONFIG_HZ_1000, and
> Arch Linux uses CONFIG_HZ_300. It became clear to me that systemd was
> not ready for prime time, it wasn't thoroughly tested in a lot of
> machines, and if you have problems Lennart Poettering will blame you
> (PulseAudio sounds familiar?).

Do you have a link to a proper bug report for this issue? I tried reading
the Google+ thread but I couldn't stomach how rude you were in each of your
messages (including the first one) so stopped reading.

> systemd was the reason I stopped using Fedora in the first place; when
> they moved to it my machine stopped booting reliably. My configuration
> was non-standard (a single encrypted partition), so I guess they never
> tested that. Similarly, I expect many Arch Linux users to bite these
> corner-cases.

Please note that we have waited much longer than Fedora did to make sure
the corner cases have been taken care of. Is this problem still an issue,
or is it just FUD? Link to (current) bug report?

> Finally, it's much harder to debug. If you have a problem you will not
> be able to open a script and figure out what is happening, and perhaps
> modify it, and debug it. You would be greeted with an unmodified
> binary, and the source code would be along these lines:
>
>
http://cgit.freedesktop.org/systemd/systemd/tree/src/remount-fs/remount-fs.c

As someone who has spent a lot of time debugging both, I much prefer
systemd. I think you are being disingenuous here, surely you don't have a
problem reading C?

> I'm sure in due time systemd will be ready, and will have nice
> advantages, but I doubt that's the case right now. Has anybody looked
> into the CONFIG_HZ issue? I doubt that.

This is the first I hear of it. I'd be interested to follow up if there is
a proper bug report without unnecessary hostility.

> I was expecting more from the Arch Linux community, something along
> the lines of Google's analysis to pick to mercurial[2], but so far I
> have only seen a couple of people saying +1 in the development mailing
> list, with barely any explanation at all. Such an important move (one
> that might make users' machines stop booting) should warrant at least
> an analysis of some sort, with clear advantages. Would it not?

We provided systemd optionally for a long time, as you know. Its pros and
cons have been discussed at the various making lists at great length. A
significant portion of our userbase has switched to it, and no serious
issues seem to remain, based on the feedback we have been getting. Each dev
will have had the possibility of trying it, and researching it. They will
have done their own analysis on which the +1s are based. I see no value in
providing an official public analysis. That's not how we work, and it would
not help in the decision making at this point.

That's not to say that an analysis would not be an interesting read, and
I'm sure people like Allan our Jason will provide some excellent blog posts
about this at some point.

> At the moment I am unconvinced; does systemd has any *real* advantage?
> I don't think so; the potential of breakage outweighs the "supposed"
> advantages, and I think a proper analysis would show that.

If you find any issues, please report bugs. Except for that, all I can say
is that no one set out to convince you, and I'm sure Google will find you
discussions/analysis/code if you are genuinely interested.

Tom
 
Old 08-15-2012, 05:50 AM
Tom Gundersen
 
Default Think twice before moving to systemd

On Aug 15, 2012 7:35 AM, "Tom Gundersen" <teg@jklm.no> wrote:
> On Aug 15, 2012 3:35 AM, "Felipe Contreras" <felipe.contreras@gmail.com>
wrote:
> > I tried systemd a while ago in a brand new machine with Arch Linux and
> > the boot was *much slower*. After some exchanges with Lennart
> > Poettering and other people in Google+[1], it became clear I was on my
> > own. Eventually I found the culprit: Fedora uses CONFIG_HZ_1000, and
> > Arch Linux uses CONFIG_HZ_300. It became clear to me that systemd was
> > not ready for prime time, it wasn't thoroughly tested in a lot of
> > machines, and if you have problems Lennart Poettering will blame you
> > (PulseAudio sounds familiar?).
>
> Do you have a link to a proper bug report for this issue? I tried reading
the Google+ thread but I couldn't stomach how rude you were in each of your
messages (including the first one) so stopped reading.

Ok I we've back and read to the end. The last message contained interesting
info. There is likely more to it, as I have not been able to reproduce
this, but still, something with looking into. As to out kernel options, if
there are good reasons to change any of them, open feature requests
(working around bugs us not necessarily a good reason).

Tom
 

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