X.Org Server To See More API/ABI Breakage

[liam]

It was a reply to uid313's comment not yours. He made a fanboi comment, and I corrected him.

If I paraphrased Keith as "An possibly imperceptible performance boost", seems like a contradiction in terms to me.

The thing you might have a couple context switches, but you might also have a few more introduced elsewhere like the input paths, the latency might go up as well as the throughput.

Keith was engaging in a bit of marketing really, since no measurements are possible at this point. I generally prefer my performance boosts to come with a measureable difference, and I don't mean gtkperf gets faster, since nobody has ever correlated that with a real world difference.

wayland won't magically speed-up X rendering, the same operations happen. In fact something like SNA would speed it up a lot more than wayland, since it actually tries to accelerate X rendering, where wayland does nothing different wrt X rendering really vs having a compositing manager running on X now.

Dave.

I had a feeling you were responding to the seeming fanboi comment and, I imagine, you encounter that sort of thing a lot. As I think I said, my only concern was that what you said seemed to be contradicting something I'd read recently (Keith's comment). Now, while I would argue that performance boosts need not be perceptible, they at least need be measurable but I wasn't aware that Keith was speaking from a marketing perspective. That clears things up a bit and helps me to understand your comment.
I, too have been wondering about the effect Wayland's input handling would have with the X clients but I've not read much about that, so I could easily see that negating at least some of the gains Wayland provides X clients on the display side.
Lastly, I reiterate that I understand there is no magic going on. I repeat, though I haven't looked behind the curtain, I believe there IS a normal person there!
The advantages Wayland provides X clients is simply fewer context switches (though only possibly, as I agreed earlier, we'll have to see how things work out) and synchronization guarantees (though we have those with a modern, desktop that is handled by an opengl library like clutter in combination with dri clients).
If I am mistaken in any of this, feel free to correct me b/c I'd much rather be publicly corrected than to privately hold false notions.
Best/Liam

[uid313]

In fact something like SNA would speed it up a lot more than wayland, since it actually tries to accelerate X rendering, where wayland does nothing different wrt X rendering really vs having a compositing manager running on X now.

SNA is only for Intel / Sandy Bridge only or can be used for AMD, Nvidia, etc too?

[ninez]

Clearly we have a bit of a communication problem here

Maybe, maybe not.. When you asserted that KP is leaning towards a performance boost, i don't see that at all;

Fair enough that he didn't say it would definitely improve performance, but the fact that Keith Packard even said it makes it *more than a little likely* to be the case.

KP did NOT say it was 'more than a little likely'. he said there could be a performance boost. he also said it more likely that it wouldn't even be something imperceptible. And as dave pointed out. His statements seem somewhat in contradiction ~ which is better than what i said of them being 'ambiguous / foggy '. I also tend to agree that it sounds like marketing and hype ~ since there isn't a way at this point to back up that claim.

I don't feel like I misrepresented KP. What I said is technically true. KP, being paraphrased, thinks there could be a performance increase, and I gave the reasoning, which was consistent with what the quote says. The only sticking point is that I failed to specify that it wasn't a certainty, but I did specify that any improvements would likely be minor (whether or not that is a "real performance boost" doesn't matter).
Does that make sense?

But i think you are misrepresenting what he is saying and i don't think it is consistent with KPs comment. I think i have a reasonable grasp on the english language (which is my native tongue), and from reading what he said - i didn't come to the same conclusion (as you). Maybe i am wrong, but it really didn't come across that he thinks there (more than likely) will be some sort of tangible performance boost, it sounded like nothing more than a possibility (with no data to support it, which is (obviously) in itself very problematic). One always needs data/facts to back up claims, without it the claim is nothing more than a belief / hunch / faith / etc. I mean if i told you i was psychic ~ you would want proof of it. You wouldn't just accept that i am psychic because i said so. Which goes back to one of my first statements;

"I will believe it, when i see it".

wayland won't magically speed-up X rendering, the same operations happen. In fact something like SNA would speed it up a lot more than wayland, since it actually tries to accelerate X rendering, where wayland does nothing different wrt X rendering really vs having a compositing manager running on X now.

This is what i thought Dave was implying with the 'magic bullet' statement. I didn't think he was talking about things like cairo. I thought he was talking about X acceleration in wayland. So i think this may have also been a point of miscommunication between us.

and by the way Liam. I do quite enjoy our interactions, even when you and i may disagree on something or have different ideas ~ we always keep our conversations clean and civil, which is nice.

cheerz

[airlied]

It was a reply to uid313's comment not yours. He made a fanboi comment, and I corrected him.

If I paraphrased Keith as "An possibly imperceptible performance boost", seems like a contradiction in terms to me.

The thing you might have a couple context switches, but you might also have a few more introduced elsewhere like the input paths, the latency might go up as well as the throughput.

Keith was engaging in a bit of marketing really, since no measurements are possible at this point. I generally prefer my performance boosts to come with a measureable difference, and I don't mean gtkperf gets faster, since nobody has ever correlated that with a real world difference.

wayland won't magically speed-up X rendering, the same operations happen. In fact something like SNA would speed it up a lot more than wayland, since it actually tries to accelerate X rendering, where wayland does nothing different wrt X rendering really vs having a compositing manager running on X now.

Dave.

But of course anyone who studied how wayland and X works would know this already.....

Dave.

[airlied]

Clearly we have a bit of a communication problem here
My problem with Dave's comment was his seeming dismissive tone with respect to Wayland, X, and performance improvement. While I certainly agree about it no being a magic bullet, I think such a statement doesn't have a lot meaning behind it in that display managers are complicated enough that I couldn't imagine one being both capable and easy enough to implement so as to qualify for magic bullet status. To counter his rather blunt assertion of something that is, at the very least, uncertain, I used KP's comment. While I have absolutely nothing but respect for Dave, his knowledge, and contributions, I think this particular area is one which KP is a bit more involved in, or, at a minimum, enough of an expert to cause a bit of doubt with regard to Dave's comment.
Now, I imagine the point Dave was making was that people shouldn't expect Wayland to magically speed up, say cairo, without subequent work being done elsewhere (like, in cairo). In short, a compositor/input handler can be a bottleneck, but it isn't necessarily, and in Linux's case isn't, the biggest one.
Lastly, since entropy posted the actual article, and I agreed that he got the right one, I'm not sure why we're having this disagreement. I don't feel like I misrepresented KP. What I said is technically true. KP, being paraphrased, thinks there could be a performance increase, and I gave the reasoning, which was consistent with what the quote says. The only sticking point is that I failed to specify that it wasn't a certainty, but I did specify that any improvements would likely be minor (whether or not that is a "real performance boost" doesn't matter).
Does that make sense?

It was a reply to uid313's comment not yours. He made a fanboi comment, and I corrected him.

If I paraphrased Keith as "An possibly imperceptible performance boost", seems like a contradiction in terms to me.

The thing you might have a couple context switches, but you might also have a few more introduced elsewhere like the input paths, the latency might go up as well as the throughput.

Keith was engaging in a bit of marketing really, since no measurements are possible at this point. I generally prefer my performance boosts to come with a measureable difference, and I don't mean gtkperf gets faster, since nobody has ever correlated that with a real world difference.

wayland won't magically speed-up X rendering, the same operations happen. In fact something like SNA would speed it up a lot more than wayland, since it actually tries to accelerate X rendering, where wayland does nothing different wrt X rendering really vs having a compositing manager running on X now.

Dave.

[liam]

I don't disagree with his reasoning... I disagreed with what you said to Dave Arlie (who is also someone i would consider an 'expert'). Everything Kieth said was *very ambiguous*, meaning he didn't actually say anything about a concrete performance boost. Furthermore, he said "the effect will likely be imperceptible, but it could be faster." So it will LIKELY be impercptible ~ that doesn't sound re-assuring, as far as any real performance boost. ..and the rest of that statement is speculative.

does that clear up what i meant?

Clearly we have a bit of a communication problem here
My problem with Dave's comment was his seeming dismissive tone with respect to Wayland, X, and performance improvement. While I certainly agree about it no being a magic bullet, I think such a statement doesn't have a lot meaning behind it in that display managers are complicated enough that I couldn't imagine one being both capable and easy enough to implement so as to qualify for magic bullet status. To counter his rather blunt assertion of something that is, at the very least, uncertain, I used KP's comment. While I have absolutely nothing but respect for Dave, his knowledge, and contributions, I think this particular area is one which KP is a bit more involved in, or, at a minimum, enough of an expert to cause a bit of doubt with regard to Dave's comment.
Now, I imagine the point Dave was making was that people shouldn't expect Wayland to magically speed up, say cairo, without subequent work being done elsewhere (like, in cairo). In short, a compositor/input handler can be a bottleneck, but it isn't necessarily, and in Linux's case isn't, the biggest one.
Lastly, since entropy posted the actual article, and I agreed that he got the right one, I'm not sure why we're having this disagreement. I don't feel like I misrepresented KP. What I said is technically true. KP, being paraphrased, thinks there could be a performance increase, and I gave the reasoning, which was consistent with what the quote says. The only sticking point is that I failed to specify that it wasn't a certainty, but I did specify that any improvements would likely be minor (whether or not that is a "real performance boost" doesn't matter).
Does that make sense?

[johnc]

One thing's for sure... when I get my Geforce 690 there's gonna be a performance boost... muaha

[ninez]

Fair enough that he didn't say it would definitely improve performance, but the fact that Keith Packard even said it makes it more than a little likely to be the case. I mean, is there anyone who is more familiar with both X and Wayland than him?
I don't typically like appeals to authority, but people at the conference had ample chance to contradict him (and there were most definitely people there who would be in a better position than either of us to contradict him), so I take that to mean his reasoning was sound, and barring something unforeseen, the expectation of a small performance increase is existing in the minds of the experts.
All that aside, his reasoning makes sense. What part of that do you disagree with?

I don't disagree with his reasoning... I disagreed with what you said to Dave Arlie (who is also someone i would consider an 'expert'). Everything Kieth said was *very ambiguous*, meaning he didn't actually say anything about a concrete performance boost. Furthermore, he said "the effect will likely be imperceptible, but it could be faster." So it will LIKELY be impercptible ~ that doesn't sound re-assuring, as far as any real performance boost. ..and the rest of that statement is speculative.

does that clear up what i meant?

[liam]

Keith never says in that Article that Wayland WILL have a performance boost. He says he has no numbers to back the claim, that it MAY be faster and that it will likely not even be noticeable. I don't know where you got the idea he claims otherwise. It sounds like a hypothesis or hunch and is very foggy at best.

Fair enough that he didn't say it would definitely improve performance, but the fact that Keith Packard even said it makes it more than a little likely to be the case. I mean, is there anyone who is more familiar with both X and Wayland than him?
I don't typically like appeals to authority, but people at the conference had ample chance to contradict him (and there were most definitely people there who would be in a better position than either of us to contradict him), so I take that to mean his reasoning was sound, and barring something unforeseen, the expectation of a small performance increase is existing in the minds of the experts.
All that aside, his reasoning makes sense. What part of that do you disagree with?

[ninez]

That's not what Keith Packard said. See the april lwn article (sorry I don't have the link).
The reasoning was that direct rendering would never deal with X (so little real change there) but X drawing would stay vigoursly in process requiring a context switch only once every vsync, and them it only hands off a handle rather the buffer content.
Not a huge improvement, but certainly not a performance regression.

Keith never says in that Article that Wayland WILL have a performance boost. He says he has no numbers to back the claim, that it MAY be faster and that it will likely not even be noticeable. I don't know where you got the idea he claims otherwise. It sounds like a hypothesis or hunch and is very foggy at best.

EDIT: i also don't think anyone claimed there would be a regression. I did point out that for me having to switch from using Nvidia to Nouveau in order to use Wayland meant that any 'performance boost' really didn't mean anything because switching from nvidia 307.11 binary driver to using Nouveau is a HUGE performance regression. ~ which is true, but has nothing to do with Wayland itself.