Windows 8 High DPC latency Fix

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by Penal Stingray, Jan 27, 2013.

  1. Von Dach

    Von Dach Master Guru

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    Scenarios with Useplatformclock No are best, BIOS HPET On/Off in Win8 doesn't matter if you have a invariable TSC.

    Performance counter frequency is not important, what you want is the lowest Time for QueryPerformanceCounter call.

    Thanks Vbs for your intakes, that's little tool was new to me and that blog was very interesting.

    I did tests with Useplatformtick and Tscsyncpolicy but they didn't change anything in PC Clock Timing 3.1.1.
     
  2. -Tj-

    -Tj- Ancient Guru

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    Hm i saw a difference, with use platform clock it was ~ 520us with it deleted 14us

    In both cases HPET 64bit enabled in bios.
     
  3. Vbs

    Vbs Master Guru

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    Yep, that about sums it! :D

    About the new Windows 8 useplatformtick, I guess it will be disabled by default in the case of the invariant TSC (When Nahalem+ get the RESET signal they all start counting from 0 and are guaranteed several years without overflow), but one could use it to force sync to HPET? Interesting, could be a way to use QPF with TSCs on older processors, and still be sure they are in-sync.
    As for tscsyncpolicy, I would guess Enhanced would be used on Nahalem+ and Bulldozer+, but it's interesting if they found any workarounds for the TSC sync problems on older processors.
     
  4. marcosamerio

    marcosamerio Master Guru

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    ¿? :)
     

  5. marcosamerio

    marcosamerio Master Guru

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    Thank u Von for the explanation

    Bye
     
  6. Mineria

    Mineria Ancient Guru

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    See, using /disabledynamictick and /useplatformclock does not make a difference DPC wise on my end, it stays very low with either combination.
    With /useplatformclock set to Yes TimeForGetTickCount is higher in that tool Vbs posted here, but overall gameplay is smoother on this rig than just with /disabledynamictick set to Yes.
    So either do my games here rely on HPET as the reference or something else is up that isn't covered by the shown documentation.

    [​IMG]

    This is with NIS running.

    I tried the complete opposite with HPET off in the BIOS and disabling usplatformclock and tick, but that gives me some stutter while moving in game, go figure.
     
    Last edited: Feb 23, 2013
  7. marcosamerio

    marcosamerio Master Guru

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    Thanks for taking ur time to explain me, but unfortunaly i cant test this

    settings in windows 7 because it says me its an invalid command, only

    Useplatformclock=false let me w7 to change but i cant test more far

    of this tweak to see if i can improve more my perfomance.

    Bye and thanks again Mineria for the explanation
     
  8. mbk1969

    mbk1969 Ancient Guru

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    But did you try with HPET 'on' in BIOS and useplatformclock 'false' ?
     
  9. Vbs

    Vbs Master Guru

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    Come on guys... are we discussing timer responses in the order of nanoseconds (10^-9) mixed with feelings of "smoothness"? Seriously?! Lol! :D

    Anyone that wishes to contribute empirical data, please report frame latency results when using different timers (measurable "smoothness"), otherwise the debate is really not worth it imho.

    More info on how to get frame latency results can be read here:
    http://www.neogaf.com/forum/showthread.php?t=512976
    http://www.tomshardware.com/reviews/gaming-processor-frame-rate-performance,3427-2.html
     
  10. Mineria

    Mineria Ancient Guru

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    It doesn't cover capturing controller input latency and jitter together with the fps, neither can I find software that can do just that.
    In addition there should be added network latency, since most games that I play are played online.
    Without the whole data it doesn't give a clear picture, right?
     

  11. Radical_53

    Radical_53 Ancient Guru

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    Frame latency is only good for "smooth", it doesn't cover "snappy" though :p
     
  12. Von Dach

    Von Dach Master Guru

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    Well, it look that Mineria is right.

    BF3, Win8, Disabledynamictick Yes, HPET On, Useplatformclock No, is noticeably smoother/snappier than HPET Off.
    Even if PC Clock Timing don't report difference.
    My guess is that the GPU use it in some way if available.
    Which make sense, HPET is nearer (on chipset) than CPU TSC.
    Possible?

    Even my Razer Lycosa keyboard don't respond as good with HPET Off. I feel latency between what happen at the screen and keys pressed.

    Anyway for me now the best setting is HPET On, Disabledynamictick Yes and Useplatformclock still not there (No).
     
    Last edited: Feb 24, 2013
  13. xdnbkingx

    xdnbkingx New Member

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    I'm having the same problems :(

    Followed the what everybody has said and tried the same things and some help lower it.

    I found ANOTHER big problem and disabling it helped ALOT...

    Norton Intrusion Prevention.

    Disable it and watch the latency DROP.

    Could somebody else confirm this for me awell?

    Currently i have ALL power saving options off on bios including SpeedStep. And HTEP On in bios and False on CMD and Dynamictick off aswell.
    i want to get rid of these spikes though as there annoying as hell!
     
  14. Lodingi

    Lodingi Member

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    Can anyone tell me where to begin? The command suggestions do not help.


    [​IMG]

    [​IMG]
     
  15. -Tj-

    -Tj- Ancient Guru

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    ^
    USB disk?


    Its saying there is something wrong with usb 1.0 and 2.0 ports..
     

  16. mbk1969

    mbk1969 Ancient Guru

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    Switch LatencyMon UI to the page "Drivers" and post its picture
     
  17. mbk1969

    mbk1969 Ancient Guru

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    Even if you mean that GPU BIOS code can use HPET or TSC, how chipset can be nearer to GPU if latter is connected to PCIE controller at CPU???


    EDIT: I guess we can assume that MB BIOS can use HPET or LAPIC for its own (chipset) timing management... But it could be only chipset SouthBridge`s timing management since NorthBridge is implemented at CPU.
     
    Last edited: Feb 24, 2013
  18. Vbs

    Vbs Master Guru

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    A quick recap :D

     
  19. Vbs

    Vbs Master Guru

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    But it will give a better picture than just subjective smoothness right? :)
     
  20. tsunami231

    tsunami231 Ancient Guru

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    Each computer is diffrent what is good for one is not always good for another pc. And what is this useplatformclock=NO last i check it TRue,False or deleted value.

    If a cpu supports iTSC its used reguarless, what you set.

    For me Useplatfromclock=true other wise I get huge 1000+us spikes

    While time for QueryPerformanceCounter() call. might be 11ns with False I get 1000+us spikes and True would be like 750ns there are no spikes at all. Either way the clock speed is always the CPU speed if the cpu supports iTSC. I rather have the no spikes, Cause I dont see a difference either way other then the spikes

    disabledynamictick is win8 only or 7 too?
     
    Last edited: Feb 24, 2013

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