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khumba
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PostPosted: Thu Apr 23, 2015 12:37 am    Post subject: Re: kdbuswreck Reply with quote

miket wrote:
There you go. systemdamage and kdbuswreck.


I like "dbust":

One Thousand Gnomes wrote:
If the userspace folks choose to continue to implement dbust over it but the kernel layer is clean and generic then all is good, because someone can replace dbust with something better. If its got dbust hard wired into it then its a complete mess.
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PostPosted: Thu Apr 23, 2015 12:42 pm    Post subject: Reply with quote

From lwn.net kdbuswreck article:

Quote:
attempt to derive a bit of light from the massive amounts of heat that have been generated so far


That's not a biased statement at all, is it?
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PostPosted: Thu Apr 23, 2015 3:54 pm    Post subject: Reply with quote

It's funny to see LP whining about that article (still behind the paywall), and complaining about the title "The Kdbuswreck". :)

I didn't know that "mezcalero" was Poettering; it explains quite a bit from comments to articles I've read on LWN.
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PostPosted: Thu Apr 23, 2015 4:31 pm    Post subject: Reply with quote

Boy he's really touchy. A bus wreck does not assume that there was something wrong with the bus. Though it can be the driver's fault .... and LP is driving the Kbus .... guess he's saying the light turned red too soon.
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PostPosted: Thu Apr 23, 2015 4:33 pm    Post subject: Reply with quote

Shamus397 wrote:
It's funny to see LP whining about that article (still behind the paywall), and complaining about the title "The Kdbuswreck". :)

I didn't know that "mezcalero" was Poettering; it explains quite a bit from comments to articles I've read on LWN.


I rather like that "One Thousand Gnomes" seems to be Alan Cox.
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PostPosted: Fri Apr 24, 2015 11:23 am    Post subject: Reply with quote

Shamus397 wrote:
I didn't know that "mezcalero" was Poettering; it explains quite a bit from comments to articles I've read on LWN.

Could it be finally that he doesn't that much crazy fan, but a lot of nickname???

(don't read this if you are easy scare): "Could it be that ulenrich is... LP!!!"
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PostPosted: Fri Apr 24, 2015 7:25 pm    Post subject: Reply with quote

@krinn: Do you know that people with technical doubts in the whole *kit story are discredited with the "conspiracy theory" argument?
You make it too easy for some to fasttalk around the technical facts...
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PostPosted: Fri Apr 24, 2015 8:03 pm    Post subject: Reply with quote

mv wrote:
@krinn: Do you know that people with technical doubts in the whole *kit story are discredited with the "conspiracy theory" argument?
You make it too easy for some to fasttalk around the technical facts...

I don't think, even the lamest one, would use a small taunt/funny quote to use it to backup any "conspiracy theory". Even someone not knowing ulenrich may get it easy.
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PostPosted: Fri Apr 24, 2015 8:12 pm    Post subject: Reply with quote

krinn wrote:
Shamus397 wrote:
I didn't know that "mezcalero" was Poettering; it explains quite a bit from comments to articles I've read on LWN.

Could it be finally that he doesn't that much crazy fan, but a lot of nickname???

(don't read this if you are easy scare): "Could it be that ulenrich is... LP!!!"

I doubt LP was able to produce constantly over the years as much invalid bugs as I have done:
https://bugs.gentoo.org/buglist.cgi?email1=%20eulenreich%40gmx.de&emailreporter1=1&list_id=1822580

And just for the record, there is a dbus-kdbus benchmark comparison available from Tizen crowd:
http://download.tizen.org/misc/media/conference2014/slides/tdc2014-kdbus-in-tizen3.pdf
page 10 - It depends on the messages size - as expected.
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PostPosted: Fri Apr 24, 2015 9:34 pm    Post subject: Reply with quote

Shamus397 wrote:
It's funny to see LP whining about that article (still behind the paywall), and complaining about the title "The Kdbuswreck". :)


LP wrote:
Also, I don't think calling kdbus a "wreck" is appropriate at all.

corbet wrote:
...and I never did that. The title refers to the discussion, not the technology.
....
With regard to the title...perhaps it was a bad choice, but "buswreck" (or "trainwreck") is a fairly common English term for an unfortunate situation. I still believe that you have to stretch pretty hard to say that "The kdbuswreck" (note "the") somehow refers to the code.

Germans associate "wreck" with "Schiffswrack" - a ship stranded on the shore. But later on
jjmarin wrote:
I agree that "The kdbuswreck" is a misleading title, IMHO, I think the title should be more precise to convey the general meaning of the article, maybe something like "The kdbus debate wreck"... anyway, I'm sure there must be a much better suggestion for the title :-)


Perhaps following correction given by Linus himself solves the kdebuswreck debate:
http://lkml.iu.edu/hypermail/linux/kernel/1504.2/04915.html
Quote:
No Greg.

Just remove the shit. Really. Take out the command line and the task
name. You already admitted that there is no actual valid use for it.

We don't add crap that then has to be disabled with secuirity rules
just because it was a bad interface. Just make the interface not do it
in the first place. It's that simple.

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truekaiser
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PostPosted: Fri Apr 24, 2015 11:21 pm    Post subject: Reply with quote

ulenrich wrote:

Perhaps following correction given by Linus himself solves the kdebuswreck debate:
http://lkml.iu.edu/hypermail/linux/kernel/1504.2/04915.html
Quote:
No Greg.

Just remove the shit. Really. Take out the command line and the task
name. You already admitted that there is no actual valid use for it.

We don't add crap that then has to be disabled with secuirity rules
just because it was a bad interface. Just make the interface not do it
in the first place. It's that simple.


At which point gkh cries, STOP OPPRESSING ME!!1!
and gets linus removed via the standard of conduct patch he rammed through earlier..
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PostPosted: Sat Apr 25, 2015 1:23 pm    Post subject: Reply with quote

ulenrich wrote:
And just for the record, there is a dbus-kdbus benchmark comparison available from Tizen crowd:
http://download.tizen.org/misc/media/conference2014/slides/tdc2014-kdbus-in-tizen3.pdf
page 10 - It depends on the messages size - as expected.

Oh jeez; that's as about as useful as a claim from a manufacturer that some new product in the same range is better than their existing pile of turd.

A better comparison was the one between dbus, Gnome's ORB, and dcop. ie alternative technologies doing the same thing.

So in this case, a comparison between kdbus and TIPC is what's needed. Anything else is just propaganda^W advertising^W marketing^W "communicating" (nonsense.)

I see where krinn is coming from: you unfailingly repeat the same old gloss that we've heard before, and never address the substantive technical issues, when it comes to anything Poeterring-related.

I'm tired of repeating the same old URLs over and over. If you want to counter the claims, read them and just for a change, show us you've read them in the arguments you make.
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PostPosted: Sat Apr 25, 2015 1:30 pm    Post subject: Reply with quote

truekaiser wrote:
At which point gkh cries, STOP OPPRESSING ME!!1!
and gets linus removed via the standard of conduct patch he rammed through earlier..

It's much more insidious than that; the whole idea is to set the tone for when Linus retires/dies.

Once he's gone, no-one else is going to have any sort of standing to simply talk straightforwardly, instead of couching everything in politically-(in)correct vague, which as we all know is exactly how corporates take over in the background.
Everyone ends up self-censoring, and their headspace is wasted on that, instead of correcting mistakes.

Multinationals play a long game, while forcing everyone else to focus on last quarter's results, or next week's shopping.

Meanwhile, "I can't tell Linus, but I sure as hell can tell you."
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PostPosted: Sun Apr 26, 2015 10:45 am    Post subject: Reply with quote

oh I like this one http://lkml.iu.edu/hypermail/linux/kernel/1504.2/04649.html

Quote:
> Did I miss anything else here? Are there any technical reasons I'm
> forgetting about for why this can't be pulled in as-is for this merge
> window?

Like the outstanding NACKS ?

Greg - you are sounding like you have some kind of special entitlement to
ignore the way this works for everyone else. If you are feeling
frustrated, annoyed and led up several avenues at once then welcome to
the world of every other submitter who doesn't think have some kind of
magic stage door pass to get their crap in the kernel when there
are core maintainers asking hard and unanswerd questions and who have
nacked it.

There's no huge hurry. There are a bunch of things like the interactions
with cgroups, and the privilege and capability model which need careful
examination. Slipping it one release to get that right isn't a big deal -
it's not even as if you can't use hardware without it as with a driver
missing a merge - this is just a performance tweak.

Alan
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PostPosted: Sun Apr 26, 2015 11:45 am    Post subject: Reply with quote

http://lkml.iu.edu/hypermail/linux/kernel/1504.2/04853.html
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PostPosted: Sun Apr 26, 2015 11:54 am    Post subject: Reply with quote

Lol standard approach to build a system...
The number of times I have crafted a large analogue circuit in say Matlab, saber, simetrix ONLY for it to not run (damn Jacobian matrix...) Wasting days...

Only to start from scratch, build it up submodule by submodule with a suitable testbench strapped around to check it... Only for the complete model to work. 1st looks show there to be no obvious differences but there must be
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PostPosted: Sun Apr 26, 2015 3:13 pm    Post subject: Reply with quote

mrbassie wrote:
http://lkml.iu.edu/hypermail/linux/kernel/1504.2/04853.html
And three days later, no reply.
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PostPosted: Sun Apr 26, 2015 3:20 pm    Post subject: Reply with quote

Actually the discussion is on the next archive page over. Here's the link to the start of the kdbus chain for this week. http://lkml.iu.edu/hypermail/linux/kernel/1504.3/00006.html (Haven't seen anything posted for yesterday, the 25th, though I am thinking it's just a delay before it gets updated on this archive.
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PostPosted: Sun Apr 26, 2015 6:20 pm    Post subject: Reply with quote

mrbassie wrote:
http://lkml.iu.edu/hypermail/linux/kernel/1504.2/04853.html
Very interesting read, especially this:
Quote:
This code has astonishingly complex interactions with all kinds of other
kernel subsystems and concerns. As a community we should understand
them and accept them before letting them in.

The only way I have seen anything make meaninful progress with those
kinds of interactions is for the pieces to be teased apart. And then
the code incrementally added to with all of the right people being
pulled into the discussion.

Seems like he's saying they need to break their monolithic mess into small pieces that each...Oh, I don't know..."do one thing and do it well"? ;) With those folks pigs will fly first I think. That philosophy somehow seems to be lost on everyone these days. I was reading an article this morning about Ubuntu 15.04 moving to systemd and the "controversy". The article totally white-washed it saying that systemd wasn't monolithic because it "creates 69 binaries"...what a flaming load of crap.

Tom
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PostPosted: Mon Apr 27, 2015 9:58 am    Post subject: Reply with quote

Quote:
This code has astonishingly complex interactions with all kinds of other
kernel subsystems and concerns. As a community we should understand
them and accept them before letting them in.


This is the most frightening part of their push to have it in the kernel so quickly.

It touches all kinds of subsystems.
Which brings up the question "is that really needed" for dbus
or is this just a slight of hand to get more control over kernel pieces
and somehow filter them through sysd thereby cutting out any and all other init systems.
ie. a wrapper around the kernel...long live sysd. :roll:

I don't think they want people, especially the kernel devs to see what the true interactions
with all the subsystems is.

Unlike GKH's whine, I don't trust the ones who wrote kdbus, I don't trust their motives,
I don't trust GKH's push to have it in come hell or high water without any meaningful reviews.

Nack, Nack, Nack...ad infinitum.
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PostPosted: Mon Apr 27, 2015 10:46 am    Post subject: Reply with quote

Anon-E-moose wrote:
Quote:
This code has astonishingly complex interactions with all kinds of other
kernel subsystems and concerns. As a community we should understand
them and accept them before letting them in.


This is the most frightening part of their push to have it in the kernel so quickly.

It touches all kinds of subsystems.
Which brings up the question "is that really needed" for dbus
or is this just a slight of hand to get more control over kernel pieces
and somehow filter them through sysd thereby cutting out any and all other init systems.
ie. a wrapper around the kernel...long live sysd. :roll:

I don't think they want people, especially the kernel devs to see what the true interactions
with all the subsystems is.

Unlike GKH's whine, I don't trust the ones who wrote kdbus, I don't trust their motives,
I don't trust GKH's push to have it in come hell or high water without any meaningful reviews.

Nack, Nack, Nack...ad infinitum.


Hanlon's razor...
They probably did that because they are userland coders and not use to atomic structure. The problem is if it went in as-is those tentrils would probably start getting abused. There is no need for it to start linking across everything... its a messagebus Userland <> Userland .... not a Userland --> deepKernel
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PostPosted: Mon Apr 27, 2015 3:23 pm    Post subject: Reply with quote

Naib wrote:
They probably did that because they are userland coders and not use to atomic structure.

The real problem is they're not even good userland coders; they don't seem to know the POSIX base at all, let alone the rest of the UNIX world.
Consequently, they are blinkered in their approach; to put it mildly.
Quote:
The problem is if it went in as-is those tendrils would probably start getting abused.

s/probably/definitely/ -- if there's a way to make money doing something, then someone will do it, even if most of us think it reprehensible.

If you think that's far-fetched, consider the milieu most of these nubs come from (Windoze) for the archetype of where RedHat is going.
Quote:
There is no need for it to start linking across everything... its a messagebus Userland <> Userland .... not a Userland --> deepKernel

Follow it through, and you arrive at TIPC.

Unfortunately: "You won't get round us with that design nonsense.." ;-)
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PostPosted: Mon Apr 27, 2015 11:09 pm    Post subject: Reply with quote

Linus just posted this http://lkml.iu.edu/hypermail/linux/kernel/1504.3/02040.html

Quote:
>> That said, either you're running your test on a potato, or dbus is
>> seriously screwed up. No way should it take 4+ seconds to send a 1000b
>> message to back and forth 20k times. But as mentioned, I can't even
>> see what it's doing right now.
>
> Whee! I'm typing this email on a potato!

No, I think you're right, there's the other non-potato choice: "dbus
is seriously screwed up".

That thing has almost no kernel footprint. It's spending all it's time
in user space overhead.

Quite frankly, the whole "kdbus is important for performance" seems to
be *totally* invalidated by even a minimal look at profiles for that
thing. Here's the top-15 offender list:

2.62% gdbus libc-2.20.so [.] _int_malloc
2.43% gdbus libc-2.20.so [.] free
2.31% server libc-2.20.so [.] free
2.12% gdbus libc-2.20.so [.] malloc
1.77% gdbus libglib-2.0.so.0.4200.2 [.] g_utf8_validate
1.43% gdbus libglib-2.0.so.0.4200.2 [.] g_slice_alloc
1.41% gdbus libglib-2.0.so.0.4200.2 [.] g_hash_table_lookup
1.28% server libc-2.20.so [.] _int_malloc
1.27% gdbus libglib-2.0.so.0.4200.2 [.] g_mutex_lock
1.22% gdbus libglib-2.0.so.0.4200.2 [.] g_variant_unref
1.16% server libc-2.20.so [.] malloc
1.14% gdbus libglib-2.0.so.0.4200.2 [.] g_bit_lock
1.07% gdbus libglib-2.0.so.0.4200.2 [.] g_slice_free1
1.05% gdbus libglib-2.0.so.0.4200.2 [.] g_bit_unlock
1.01% gdbus libglib-2.0.so.0.4200.2 [.] g_mutex_unlock

there's not a kernel function in sight in the top-15, and it's all
just overhead. The above is from the server side, but the client looks
similar.

If somebody wants to speed up dbus, they should likely look at the
user-space code, not the kernel side.

My guess is that pretty much the entirely of the quoted kdbus
"speedup" isn't because it speeds up any kernel side thing, it's
because it avoids the user-space crap in the dbus server.

IOW, all the people who say that it's about avoiding context switches
are probably just full of shit. It's not about context switches, it's
about bad user-level code.


:lol: LoL :lol:


and in the follow up post

Quote:
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> IOW, all the people who say that it's about avoiding context switches
> are probably just full of shit. It's not about context switches, it's
> about bad user-level code.

Just to make sure, I did a system-wide profile (so that you can
actually see the overhead of context switching better), and that
didn't change the picture.

The scheduler overhead *might* be 1% or so.

So really. The people who talk about how kdbus improves performance
are just full of sh*t. Yes, it improves things, but the improvement
seems to be 100% "incidental", in that it avoids a few trips down the
user-space problems.

The real problems seem to be in dbus memory management (suggestion:
keep a small per-thread cache of those message allocations) and to a
smaller degree in the crazy utf8 validation (why the f*ck does it do
that anyway?), with some locking problems thrown in for good measure.

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PostPosted: Mon Apr 27, 2015 11:44 pm    Post subject: Reply with quote

A good read by Andy L. http://lkml.iu.edu/hypermail/linux/kernel/1504.3/01895.html
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PostPosted: Tue Apr 28, 2015 6:53 am    Post subject: Reply with quote

Get ready for the sysd manoeuvre "kdbus is not about speed improvement its about, um, security... Wait no its about ... STOP THIS CAMPAIGN OF HATE"

Funny how they are having to review userland calls to get an idea what kdbus is suppose todo
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