Will Ps3 non-gaming features bottleneck gaming?

Discussion in 'Console Technology' started by internetboy, Feb 15, 2006.

  1. internetboy

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    Hi. I have a question for Ps3 developers. What are the resources free to developers for your games?

    It is for sure Ps3 have more Os features than 360. The more features will lock down more resources.

    This is Ms Xbl Dash reserves i saw in 360 OS thread - 5% of C1 and C2, 32mb of 512mb. Ms features are spread between 360 and MediaCE PC.

    Sony will lock down 1 spe. I think that is more powerful than C1 and C2. What about the RAM? I think it must be more than 32mb of 512mb. Psp Os lock down 8mb of 32mb. I think Ps2 Os is on the games dvd.

    I think it is a waste if 1 spe is locked and more RAM for non-gaming features will be bottleneck to gaming. Can Os run from flash memory to save Ps3 main memory?
     
  2. cho

    cho
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    what is the C2 ?
     
  3. DarkRage

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    C for core, I guess.
    C0 = main core in 360, 100% available to the developer. C1 and C2 have some power reserved to the OS (<5%)

    I don't see why PS3 OS will have more features than 360. I would bet it would be just the other way around, if any differences.

    SPEs are worse suited for running an OS than PPE. AFAIK SPEs are missing some very useful exception handling capabilities / running modes and so on. I would say core OS is expected to run on PPE, with any other "media Center" type running on several SPEs are needed.

    Flash memory is slooooow. You can save the OS (or parts of it) in Flash memory, but when running, you need it in main memory.
     
  4. Inane_Dork

    Inane_Dork Rebmem Roines
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    I posed this question in another thread, and the basic answer is that the OS running on Cell is made to guarantee a certain amount of processing power to handle whatever else is going without interfering with games.

    That's the theory, anyway. I would not be surprised at all if it turned out to be false.
     
  5. Griffith

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    this seems all wrong.

    and C1 is Xenos, aka R500, the GPU of 360.
     
  6. DarkRage

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    I think it is pretty clear C1 is naming one of the three cores of Xenon (C0, C1 and C2), and that information and names are being taken from a 3D Engine being developed by Idontrememberrightnow (it was a heavily multiphased japanese engine especific for 360)
     
  7. London-boy

    London-boy Shifty's daddy
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    Well the real name of Xenos is C1, that's why it's confusing. Now that you explain it, it makes more sense. Personally i was also confused because to ATI, Xenos is really C1.
     
  8. Titanio

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    The question isn't about the OS taking a variable amount of resources and interfering with games that way, rather whether so much would be reserved so as to "bottleneck" games. But why would you not be surprised if the mechanisms IBM has outlined to reserve resources turned out to be "false"?

    To answer the OP's question, I don't think reserving a SPU and some PPE time will "bottleneck" a game.
     
  9. London-boy

    London-boy Shifty's daddy
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    But u just know that people will come in here going "what?!!!1 first they deactivate one SPE for redundancy, then they reserve one for OS?!!11 From 8 SPE to 6... Sony robbed us!!11"
     
  10. DarkRage

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    According the documentation IBM made available last week for "compilation for Cell":
    "The PPE is primarily used in a supervisory role, or to provide OS services, for code being run on the SPEs."

    So we can expect PPE to deal with most of the OS (it is much better suited for that task than a SPE) and take 32 MB for it.
    It shouldn't be a big bottleneck... if you are able to place most of the calculation tasks to the SPEs, of course.
     
  11. Inane_Dork

    Inane_Dork Rebmem Roines
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    Which is exactly what I answered. I don't know what you read, but I directly addressed reserving resources to run background processes so that foreground processes would not be affected.

    Please, stop trying to paint me as a moron. There's no need to quote the word "false" as if it's abhorrent to your mind.

    I simply meant that having all this stuff segmented to not interfere with each other is a theory right now. And theories about runtime performance of multiple processes on multiple cores of the same CPU have a way of being wrong part of the time due to complexity. I'm not saying that Sony and IBM are stupid. Rather, that I don't think anyone can do it. There are too many variables to account for.
     
  12. Titanio

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    IBM claims to have the mechanisms in place to handle this, and I've little reason to doubt that unless you can bring further insight. Either way, as far as processes go it'd be no different than 360's situation if there were issues with juggling those, except that an entire SPU can be reserved if necessary, which might relieve the PPE compared to the work either of the OS-accomodating cores in 360 needs to do. My guess is if they're going to reserve a whole SPU, as much responsibility as possible will be offloaded to it.

    Moving to a different point raised earlier, about the demands required of the PS3 OS, they could well be higher than 360's. PS3 may need to be able to display a HD signal simultaneous with gameplay (on a second screen for example), and in handling input, may also be required to do some eyetoy/image processing, for example (which I guess would be more intensive than regular joypad input processing). I could quite easily imagine them reserving a SPU for the OS, for these reasons, not to mention the headroom it would afford them for updates going forward.
     
  13. Inane_Dork

    Inane_Dork Rebmem Roines
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    Heavy-handed appeal to authority. That's really beneath you.

    You know as well as I that what they're trying to account for is quite likely beyond human capacity to fully understand. That means there is the possibility of hiccups in performance. Appealing to IBM as some kind of carte blanche over human incapability is totally worthless. This is not about IBM.

    Exactly! I have no doubt that the 360's *stuff* could get in the way of games, even though most of it should be accounted for in testing (as opposed to the PS3).

    You're trying to make this a 360 vs. PS3 thing so that I'll fold when you point out that the situation exists on the 360 as well. Well, it didn't work. Please stop throwing fallacies my way. All I'm arguing for is the possibility of interference. Surely that idea is quite tolerable to inspection.
     
  14. Titanio

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    Well, what is it about? Maybe it's the hour of the night, but it escapes me what you are referring to. If you can provide insight here, please do. Don't spare detail. I am under the impression that cycles could be reserved, and even the timing of the OS's activity specified, and even still in all cases, that a realtime app could have priority vs the OS. If there's something lacking in that thinking or there is more to consider, please elaborate for the benefit of the thread.

    The 360 comparison was made simply because the OP introduced one and it continued. I think it's relevant if a similar situation exists there and doesn't noticeably impact the running of the system during a game, which might suggest how much we should or shouldn't worry about it.

    I'm eager to see the possibility for interference investigated and elaborated upon, if you'd care to..?
     
    #14 Titanio, Feb 15, 2006
    Last edited by a moderator: Feb 15, 2006
  15. Inane_Dork

    Inane_Dork Rebmem Roines
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    How many different tasks can the PS3 do? Switch, location-free access, PSP server, maybe a DVR, possible P2P traffic? I think that's all of them. Then, of course, there is the OS and whatever game (possibly online game) is running. Given that lots of these things are bursty and unpredictable on the clock level, do you really think IBM can plan for all contingencies? I do not. That's all there is to it.

    If you cannot see even the possibility of a problem, then there's nothing I can say to further explain, because it is terribly obvious to me.
     
  16. ERP

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    If they just said were taking 1 SPE, that's pretty deterministic.
    However even then your going to have loads on the external bus and those likely won't be.
    Having said that given just how much bandwidth Cell has to it's RAM it's probably a none issue.

    What's a bigger question is how they display that second screen and what if any graphics chip resources it takes.
     
  17. expletive

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    I think the original question was basically this...

    There's a thread that talks about the CPU utilization of the 360 CPU for things like OS, sound processing, etc. the following is what has been reported:

    -C0 is the main core and is reserved for gaming code.This is always 100% available for these tasks.
    -5% of C1 and C2 are reserved for OS, networking, USB, dashboard, etc.
    -Sound mixing encoding etc is done on C2. When maxed out at 256 channels, 25% of C2 is used.

    Will the design of Cell require things like the OS, USB, networking, and sound processing, require the use of an entire dedicated SPE(s)? It seems the 360 can devote a "portion" of its cores to such tasks, can the cell devote a portion of an SPE to these things or does one need to be dedicated for them, overkill or not...
     
  18. flick556

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    I don't expect the ps3 to be able to do all these things in the background without a performance hit. This is why they likely won't be running while a game is being played. DVR, P2P, PSP, media functions, etc. will probably only be done while not playing games. The OS would need nice pause and notify features during game play. For example if you’re playing a game and a show is set to record it should notify you and give you the option to continue playing and not record or to record. If this “notify" program is the only process running during game play I can't imagine it consuming lots of CPU resources. No different then having one more AI routine running in the game, in terms of sharing resources.

    The challenge is you need some persistent storage of the OS for when consoles go off, I’m sure Sony chose something for this. It may be costly loading the OS to/from your persistent storage medium. This is why the OS stays in memory and consumes 32mb even during game play, because it would be too costly to load and unload the OS often. So it takes memory from the game but should not affect processor performance too greatly.

    360s OS can do a bit more than this while games are played. At 5% CPU and 32mb of memory it appears they done a good job for the features Xbox live supports during game play.
     
  19. Titanio

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    flick556 - Sony has said that web browsing, media browsing and playback (music, video, photos etc.), video chat etc. will be possible simultaneous with gameplay. If the OS is given strict boundaries to work within it shouldn't adversely affect game performance.
     
  20. rabidrabbit

    rabidrabbit A Reformed Member
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    DeanoC's blog, originally linked in this thread about PS3 memory management by chris1515.
    http://www.beyond3d.com/forum/showthread.php?t=28419
    So, is the OS going to be more than the simplish "Cross Media Bar" that is found in PSP.
    How much memory does the PSP OS take? With PS3 having more built in features, can we estimate how big a PS3 "Cross Media Bar" style interface would be?
     
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