Another look at HPET High Precision Event Timer

Discussion in 'Videocards - NVIDIA GeForce Drivers Section' started by Bukkake, Sep 18, 2012.

  1. applejack

    applejack Master Guru

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    just want to get this straight, what is the supposed gain switching from

    1. bios HPET enabled, useplatformclockset true, C-States enabled.

    to

    2. bios HPET enabled, useplatformclockset true, C-States disabled.

    should it lower latencies when gaming (at max freq.) ?
    because if we're talking idle alone, I rather keep the C-States enabled, regardless of how minimal the lower CPU volt/temp gain actually is.


    BTW, this thread reminded me to take another look at DPC latencies, and apparently I was getting a 1000us spike every 5sec constantly, along with ESET NOD32 process spiking (low) cpu usage.
    LatencyMon concluded it has to do with Intel (IAStore) & nvidia drivers (also mentioned cpu power-saving features), but since NOD32 statistics kept listing some Raxco's PerfectDisk file,
    I gladly solved this mess by disabling PD's services. no more spikes and now LatencyMon agrees my system is top notch :)
    for the record I use Intel SSD for main OS, another onboard mSata Intel SSD accelerating a velociraptor via SRT, plus 3 more WD drives.
    While admittedly I don't recall suspecting latency problems on a daily basis, this behavior didn't seem limited to idle state, so I'll drop the on-the-fly ssd aware gimmicks and stick to good old on-demand defrag, which I barely need anyway.
     
    Last edited: Oct 19, 2012
  2. HonoredShadow

    HonoredShadow Ancient Guru

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    Yes sorry I was shattered lol. I mean max frequency. I'm trying to find out if it's best to leave some or all of the C-States on as when a game runs the PC steps up and latecy goes down anyway.
     
  3. tweakpower

    tweakpower Banned

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    Maybe it is, depends from system to system, i prefer without any power saving features. But i do understand you point, if latency goes up anyway, there is no real reason not to use those features, if you benefit from them without problem.
     
  4. Mineria

    Mineria Ancient Guru

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    If everything was perfect there would be no delays between entering C-states, case is, that it isn't perfect, so if you want to eliminate another factor of DPC Latency, disabling C-State is on of them.
    Remember that CPU responsiveness has affect on everything connected to your BUS, not only the CPU itself.
    Every delay makes it less responsive, that doesn't take rocket science to figure.
    Question is more how much delay you can accept.
    Although, most modern boards would have so little delays that you practically won't notice them.
     

  5. tweakpower

    tweakpower Banned

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    I think you guys have a good point. Just checked latency with DCP Latency Checker v1.3.0 and here are results:

    With HPET most of the time, latency is around 70-100us, with maximum peak at 122us.

    Without HPET latency is most of the time around 9-20us, with peak at 70us.

    Tho, it was short time testing, with playing music, videos, browsing and flash.
     
  6. tsunami231

    tsunami231 Ancient Guru

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    dont use dpc latency checker its giving incorrect numbers use latencymon
     
  7. tweakpower

    tweakpower Banned

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    Didn't know that, thanks. But, i did felt the difference in speed of PC, so, even if it give wrong numbers, it is def. better without HPET on this configuration.
     
  8. Mineria

    Mineria Ancient Guru

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    On Windows 8, on Windows 7 it always gave me the same numbers as LatencyMon
     
  9. HonoredShadow

    HonoredShadow Ancient Guru

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    Could you not just selectively turn some off but not the one that the CPU frequency is on max all the time. As long as the game pulls it out of these states and it does not go back while playing then I see no problem.

    Do you know what the others do? I have no idea. Will have to write them down and have a search online.
     
  10. tsunami231

    tsunami231 Ancient Guru

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    not for me. Dpc latency checker game me completely different numbers compared to latencymon in win7 64bit, and for alot of other people. Which why lot of people where told to use latencymon

    hpet on bios dpc checker said 10ms but latencymon said 800ms and i more incline to believe a latency checker that is updated as a opposed to one that isnt
     
    Last edited: Oct 22, 2012

  11. tweakpower

    tweakpower Banned

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    You are right, it shows dif. numbers, and it shows around 800-900 in latencymon compared to 10 in DCP latency checker on my config.

    EDIT: Those two programs are completely contradictive, DPC Latency checker shows 9-20 us without HPET, but 800-900 with, while LatencyMon shows 8-9 with HPET, and 800-900 without... go figure...
     
    Last edited: Oct 22, 2012
  12. Mineria

    Mineria Ancient Guru

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    Weird, there shouldn't be so big differences between those two, always worked pretty accurate on my old Win7 x64 installation when comparing current and highest values.
    LatencyMon is just better at giving some details, but not as good as xperf ofc.

    Results are in ┬Ás not ms, if they where ms our PC's would be real slow :)
     
  13. SLI-756

    SLI-756 Banned

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    Got this enabled now folks, thanks very much, mouse feels great now.
    Peace.
     
  14. tweakpower

    tweakpower Banned

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    Hey, i just find out that actually LatencyMon is the program that gives wrong numbers, not DCP Latency Checker, at least on mine system. But it is true that they show different numbers.

    Edited last post, with wrong numbers, here are correct ones.

    Those two programs are completely contradictive, DPC Latency checker shows 9-20 us without HPET, but 70-80 with, while LatencyMon shows 8-9 with HPET, and 800-900 without.
     
  15. SLI-756

    SLI-756 Banned

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    I was suffering strange 'micro freezes' in-game so i've just disabled it, in windows and in bios, start up seems a little faster now.
     

  16. Prophet

    Prophet Master Guru

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    I dont know of any way to prove it either way if there are only two programs that measure this.
     
  17. tweakpower

    tweakpower Banned

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    Yeah, maybe i was wrong. But it is strange at least. Anyway, keeping HPET enabled (both BIOS and OS) have some benefits over disabled, for stability, so i prefer to keep it enabled anyways.
     
  18. snorge

    snorge Member Guru

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    I've been doing some more testing with HPET on in both the bios and Win 7 and I just can't get used to the feel of it for gaming. It seems kind of like it is creating input lag. Went back to on in bios off in windows for now the default on my system.
     
  19. tsunami231

    tsunami231 Ancient Guru

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    There is no way of know which is correct dpc checker uses an older means of checking mean while latencymon use a newer way that started in vista. Like i said i more incline to believe the program that is actual updated.
     
  20. Rapyer

    Rapyer Master Guru

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    please dont start with your "i feel" ****. 1st you say your graphics lag because of dpc latency, then you say your pc lags because of a monitoring program. please educate yourself before you spout nonsense and pollute others minds


    i can tell you right now 4 things that can reduce input lag.

    disable vsync

    put render frames to 1.

    disable display scaling

    or enable triple buffering with vsync on
     
    Last edited: Oct 23, 2012

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