I can find zero documentation on what you are talking about. But I assume you would have already shared this with us if it only existed.
Synchroniszation issues with SLI and CrossFire
- Thread starter Still
- Start date
I can find zero documentation on what you are talking about. But I assume you would have already shared this with us if it only existed.
Because its "not" documented. What do you think the differences are between the profiles below?
0x02014001
and
0x02506401
Both are 2 way AFR rendering profiles. But they do something entirely different in the way SLI rendering occurs. Put 2 and 2 together. Nvidia is not going to put in detail what every one of its driver tricks for SLI are. And for reasons I would think would be pretty obvious.
Chris
So what? These are just driver profiles for applications with compatibility flags.
If there was such a flag that fixes the problem - why not share it with us?
You really dont know what you are talking about. Application compatibility flags change the way AFR is done under many circumstances.
I told you that you could "Adjust" the way that AFR is synched. I did not say you would be able to fix it entirely. Nvidia drivers have several compatibility profile flags because different games require different types of AFR and AFR syncing. You come here proclaiming that this is an enormous problem for SLI/Crossfire users. Which is a huge overstatement to say the least. You claim to have done on all this testing. . But even when I pretty much told you where to look and make changes. You just shrug it off and tell me I dont know what I am talking about. I cant tell you every specific rendering method because I am not allowed too. I'm glad you find this so humerous.
I'm done with you.
I told you that you could "Adjust" the way that AFR is synched. I did not say you would be able to fix it entirely. Nvidia drivers have several compatibility profile flags because different games require different types of AFR and AFR syncing. You come here proclaiming that this is an enormous problem for SLI/Crossfire users. Which is a huge overstatement to say the least. You claim to have done on all this testing. . But even when I pretty much told you where to look and make changes. You just shrug it off and tell me I dont know what I am talking about. I cant tell you every specific rendering method because I am not allowed too. I'm glad you find this so humerous.
I'm done with you.
Temper, temper now Chris. And you'd have to figure out which one of the "we" collective you're done with...which seems to be hard.
In other news, the sky is falling. We repeat, the sky is falling. Why this even more immense issue is ignored by ignorants worldwide is beyond us, but it undoubtedly is falling.
So why don't you simply clarify what flag has influence on the synchronization?
Because of this problem, every second frame takes MUCH longer than the frame rate suggests, sometimes even longer than with only one card.
How does this not qualify as an enormous problem if it means that most of the performance gains of SLI/CrossFire are destroyed by it?!
Sorry that I can't test something if you don't tell me what you are talking about specifically.
The profile settings he posted are game specific and thus often don't work with the apps i tested in SLI mode or they show no difference.
And yes, as I already said, I tested a tons of different profile settings and all had no effect on the synchronization problem.
Oh don't mind us, please go on. We're all just watching and enjoying the spectacle of the whole thing.
Still has very valid points, and some of the replys here sound a bit xenophobic...
Instead of providing a solution or proof that the problem does not exist, ChrisRay is talking about some obscure HEX codes and suggesting that Still should do or should have done testing with an entirely undocumented driver parameter. Not to mention the hostility of the language he is using, which is very unnecessary IMO.
Question to ChrisRay: Are you suggesting that Still should tests and benchmarks all relevant 3D engines with every single possible 8 digit HEX number in a SLI system? There are over 4 billion combinations there, so at least give him a reduced subset for the possible combinations of such a HEX number. If you are not allowed to say anything about them, why bring it up in the first place?
In particular, I wonder, if it is not more precise for ChrisRay just to say that nVidia alone can fix their AFR synchronization on a per game basis, and not to suggest that the end users should start hacking some HEX codes.
Instead of providing a solution or proof that the problem does not exist, ChrisRay is talking about some obscure HEX codes and suggesting that Still should do or should have done testing with an entirely undocumented driver parameter. Not to mention the hostility of the language he is using, which is very unnecessary IMO.
Question to ChrisRay: Are you suggesting that Still should tests and benchmarks all relevant 3D engines with every single possible 8 digit HEX number in a SLI system? There are over 4 billion combinations there, so at least give him a reduced subset for the possible combinations of such a HEX number. If you are not allowed to say anything about them, why bring it up in the first place?
In particular, I wonder, if it is not more precise for ChrisRay just to say that nVidia alone can fix their AFR synchronization on a per game basis, and not to suggest that the end users should start hacking some HEX codes.
Nope. I said that the hex values have distinct functions. Some games require different hex values to tell the driver how to predict/alternate frames. Changing certain values will change the way the driver reacts to balancing the load and syncing the frames.
I told him where to look if he was "that" concerned with this issue. To try and manipulate it. Many of these hex values are not "specific" to a single game and can overlap in functionality across various ngames and often produce different results. In performance and AFR synchronization. Nvidia provides 2 basic ways to manipulate this in the drivers already. ((AFR1, AFR2)) but theres alot more to it than that. Personally I would think this would be obvious to anyone who claims to have done as much research as this person is claiming to have.
Frankly, I dont care if you like my tone. I dont like his and I think he's made a joke out of the whole situation. But I havent used any hostile language. I've been very candor and direct. He asked me if I could clarify and the answer to that was no. The drivers provide basic functionality for AFR support in the control panel. But if you want to access the advanced functionality your going to have to get your hands dirty and play with the settings. Theres nothing obscure about these profile settings. They've been the heart of how SLI has been configured since its introduction.
The very idea that this is some huge issue and that Crossfire/SLI users are getting jipped big time. Is relatively obsurd though. People who dont like AFR and SLI wont use multi GPU. I've been administrating/moderating SLIZONE for almost 2 years now. And the number of times people pop up and say "My frames arent synced properly!" could be counted on a single hand. Yup you could say they probably "arent informed" as a reply. But even if they were I doubt they care. Because its obviously not having as large an affect as some people here trying to have you believe.
You are never going to get away from the fact that all frames dont sync up properly at all times when using AFR. Its a fact of life. I was simply providing that if someone really wants too they can go in and try manipulate base profiles and see if they can find settings that they prefer by manipulating some of these values. I do it for EQ 2 because I dont like the base profile because it's optimised for a specific way EQ 2 renders. A feature which I dont even use in the game.
Nvidia's profiling system isnt rocket science. And you can get an idea for what certain things do by looking at the games they are designed for. The reason I mention it because if someone really wants that level of control. Its there for them. There are "hardly" thousands of combinations that exist. These numbers aren't some random generation or placement like part of a slot machine.
This is ridiculous. My very first post stated that this was nothing new. Why would I post to the contrary? You will never get rid of it completely if you use AFR.
Chris
I told him where to look if he was "that" concerned with this issue. To try and manipulate it. Many of these hex values are not "specific" to a single game and can overlap in functionality across various ngames and often produce different results. In performance and AFR synchronization. Nvidia provides 2 basic ways to manipulate this in the drivers already. ((AFR1, AFR2)) but theres alot more to it than that. Personally I would think this would be obvious to anyone who claims to have done as much research as this person is claiming to have.
Frankly, I dont care if you like my tone. I dont like his and I think he's made a joke out of the whole situation. But I havent used any hostile language. I've been very candor and direct. He asked me if I could clarify and the answer to that was no. The drivers provide basic functionality for AFR support in the control panel. But if you want to access the advanced functionality your going to have to get your hands dirty and play with the settings. Theres nothing obscure about these profile settings. They've been the heart of how SLI has been configured since its introduction.
The very idea that this is some huge issue and that Crossfire/SLI users are getting jipped big time. Is relatively obsurd though. People who dont like AFR and SLI wont use multi GPU. I've been administrating/moderating SLIZONE for almost 2 years now. And the number of times people pop up and say "My frames arent synced properly!" could be counted on a single hand. Yup you could say they probably "arent informed" as a reply. But even if they were I doubt they care. Because its obviously not having as large an affect as some people here trying to have you believe.
You are never going to get away from the fact that all frames dont sync up properly at all times when using AFR. Its a fact of life. I was simply providing that if someone really wants too they can go in and try manipulate base profiles and see if they can find settings that they prefer by manipulating some of these values. I do it for EQ 2 because I dont like the base profile because it's optimised for a specific way EQ 2 renders. A feature which I dont even use in the game.
Nvidia's profiling system isnt rocket science. And you can get an idea for what certain things do by looking at the games they are designed for. The reason I mention it because if someone really wants that level of control. Its there for them. There are "hardly" thousands of combinations that exist. These numbers aren't some random generation or placement like part of a slot machine.
This is ridiculous. My very first post stated that this was nothing new. Why would I post to the contrary? You will never get rid of it completely if you use AFR.
Chris
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I'm not going to get further involved in this, but...
One, there is nothing magical about frame syncing that REQUIRES it to be unbalanced *for balanced workloads*. Obviously if the game doesn't balance stuff on purpose as an optimization, then it's often impossible - but that isn't the main case we are talking about here. However, I think it is true that there may be hardware limitations that prevent syncing from being ideally balanced.
Two, saying it's unreasonable to make a big deal out of this is wrong. Not only is it reasonable to do so, but it is necessary, because reviewers in general never talk about the disadvantages of AFR. They just put a 9600 GT SLI right next to a 8800 Ultra and compare FPS scores directly as if they were comparable. They are not! Comparing 2-way SLI vs 2-way SLI or 2-way CrossFire numbers is fair. Comparing a GX2 card to a single-chip monolithic card is not unless you insist sufficiently about the disadvantages of AFR. The same goes for Hybrid SLI/CrossFire (the performance aspects, not the power saving ones), which is an absolute disgrace once you start taking latency & syncing into consideration.
I agree with Chris that it doesn't seem to be such a big deal to SLI and CrossFire users in general. It'd be very nice to improve it, and I could never suggest a SLI rig to someone until it was - but honestly, I wouldn't even worry too much about that part. What I would worry about is how usual it has become to compare configurations with different levels of AFR (no AFR, 2-way AFR, 3-way AFR, or 4-way AFR) and do as if the FPS numbers were actually equivalent. That's obviously so wrong it's not even funny.
So yeah, in conclusion: it's worth making a big deal ut of this, let alone to be able to humiliate everyone at NV and AMD who thought Hybrid SLI/CrossFire via AFR would be a good idea. It is, in fact, an incredibly stupid idea. However, when Dell proposes (or at least proposed) CrossFired 2600 XTs on a bunch of their configs, you can see where the OEM appeal is - that doesn't mean it should be encouraged though. Quite on the contrary, it should just be fought even more vigorously as a consequence.
One, there is nothing magical about frame syncing that REQUIRES it to be unbalanced *for balanced workloads*. Obviously if the game doesn't balance stuff on purpose as an optimization, then it's often impossible - but that isn't the main case we are talking about here. However, I think it is true that there may be hardware limitations that prevent syncing from being ideally balanced.
Two, saying it's unreasonable to make a big deal out of this is wrong. Not only is it reasonable to do so, but it is necessary, because reviewers in general never talk about the disadvantages of AFR. They just put a 9600 GT SLI right next to a 8800 Ultra and compare FPS scores directly as if they were comparable. They are not! Comparing 2-way SLI vs 2-way SLI or 2-way CrossFire numbers is fair. Comparing a GX2 card to a single-chip monolithic card is not unless you insist sufficiently about the disadvantages of AFR. The same goes for Hybrid SLI/CrossFire (the performance aspects, not the power saving ones), which is an absolute disgrace once you start taking latency & syncing into consideration.
I agree with Chris that it doesn't seem to be such a big deal to SLI and CrossFire users in general. It'd be very nice to improve it, and I could never suggest a SLI rig to someone until it was - but honestly, I wouldn't even worry too much about that part. What I would worry about is how usual it has become to compare configurations with different levels of AFR (no AFR, 2-way AFR, 3-way AFR, or 4-way AFR) and do as if the FPS numbers were actually equivalent. That's obviously so wrong it's not even funny.
So yeah, in conclusion: it's worth making a big deal ut of this, let alone to be able to humiliate everyone at NV and AMD who thought Hybrid SLI/CrossFire via AFR would be a good idea. It is, in fact, an incredibly stupid idea. However, when Dell proposes (or at least proposed) CrossFired 2600 XTs on a bunch of their configs, you can see where the OEM appeal is - that doesn't mean it should be encouraged though. Quite on the contrary, it should just be fought even more vigorously as a consequence.
I (and others) could reproduce the issue on all tested games that had a SLI/CrossFire profile.How is an application made to be SLI/Crossfire friendly(Same question from back when I saw the SLI option in Call of Duty 2
Errr, that's what I said, so I'll presume you are just repeating that to make it clear we are saying the same thing...
Arun said:
There was a time when SLI was in its teething stage. You could get AFR to work in the fashion of balanced syncing in the way you are describing. The thing is it only worked with the simplest of games. And was quickly replaced. The transistion phase that phased this out was about the time the profiles became editable from the control panel ((with coolbits)) and AFR2 was also implemented. The type of AFR alot of people here seem to be asking for. Was never able to produce scaling in any titles that used things like Bloom ect.
Its pretty obvious to me. ((and I hope everyone else here)) that when you compare a single card to a dual GPU card and you are getting similar FPS and one is using AFR that the single card would be preferable. And that AFR and profiling SLI should always be a factor for people to consider when making that decision. And I whole heartedly agree with that. The advantages come specifically when you are getting performance far greater than what a single GPU is capable of. Or if you are just deciding to upgrade your system to another GPU to improve your systems performance in a later life ((this is quite common thing I see on SLIZONE)). Where the advantages outweigh the disadvantages.
I wish crossfire had as many neat ways to monkey with it as SLI sometimes.
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