Another look at HPET High Precision Event Timer

[Bukkake]

I came across this site

http://www.neowin.net/forum/topic/10...mance-and-fps/

i used to have hpet disabled in bios and it was also disabled in my windows.

now i enabled it in the bios and i enabled it in windows.

i have yet to test any games and i dont really notice any difference

my max latency in dpc latenacy check is 132 us

in the topic there is wildy different results

but with my computer in non gaming related usage i dont see any differnce at all.

[HonoredShadow]

How do you test if its enabled in windows?

[Prophet]

Originally Posted by HonoredShadow

How do you test if its enabled in windows?

You can only set it in bios. You cannot enable/disable it from windows either. Asus bioses tend to have it, other vendors you have a to have a bit of luck. I think more and more are implementing it in bios updates.

Edit: You can enable/disable hpet from the devmanager but that doesnt enable/disable it.

Edit 2.

[IcE]

Originally Posted by HonoredShadow

How do you test if its enabled in windows?

You assume it's on unless you've turned it off in the BIOS.

[WhiteLightning]

Originally Posted by HonoredShadow

How do you test if its enabled in windows?

You need WinTimerTester 1.1 to test it. its off by default (even for windows 8).
(so setting in the bios alone does nothing, has to be enabled in windows aswell).

[HonoredShadow]

Really? Oh! It is on by default on my PC but its not doing anything then?

Is it best on or off in bios and windows?

[WhiteLightning]

Originally Posted by HonoredShadow

Really? Oh! It is on by default on my PC but its not doing anything then?

Is it best on or off in bios and windows?

i really dont know. there are positive and negative reports. best is to see for yourself.
i wanted to use dpclatency checker , but since im on windows 8 its not supported as of yet. giving the wrong values

[HonoredShadow]

Well I did try with it off in the past and what i saw happen with DPC Latency tester was that my overall latency (idle) was done consistently but when I did do something like load a game or open firefox etc. then I noticed the latency spiked higher than before by quiet a bit.

This was all of course without me knowing that I had to enable it in Windows (which I have no clue how too!)

I'm sure I already had a thread on this.

[HonoredShadow]

http://forums.guru3d.com/search.php?searchid=3982593

I must have added to another thread as I can't find one I started.

I think I added to the discussion in this thread. Starting at the end of the thread and back:

http://forums.guru3d.com/showthread....highlight=hpet

[Noisiv]

Snake oil

[-Tj-]

Originally Posted by WhiteLightning

You need WinTimerTester 1.1 to test it. its off by default (even for windows 8).
(so setting in the bios alone does nothing, has to be enabled in windows aswell).

If its running at 14.31818MHz then its enabled.


And to use this 14.3mhz as the only clock open CMD (run as administrator) and type in bcdedit /set useplatformclock true


I use this option since Vista days and it never caused any issues at 90-150us, actually it helped with X-FI drivers, if i used 2MHz (HPET off) i got some 250-350us spikes time to time.

[PhazeDelta1]

Originally Posted by Noisiv

Snake oil

More like Placebo.

[kalston]

Not exactly placebo.

When I enable it in windows and get 14.3 or so mhz in wintimertester my system feels completely different. It is smoother but everything is somewhat slower and delayed. The difference is very noticeable for me (and some other people have reported the same thing on neowin forums).

And regardless of the windows configuration enabling it or not in the bios makes a slight difference in terms of DPC latency (apparently windows uses different timers by default so disabling HPET in the bios means one less conflicting timer to use and lower DPC latency). However apart from the DPC latency readings I certainly can't tell the difference in benchmarks or games between HPET ON/OFF in the bios. It's only by enabling it in both windows and the bios that I notice a BIG (and NEGATIVE) difference. Why don't you just try it for yourself? It's harmless and easy to revert the changes.

[RoadKillNL]

Running at 14.31818 MHz for me.

I enabled it not long ago. Set it to 64-Bit in BIOS and enabled it in Windows with the Command shown earlier.

Ever since i enabled it everything ingame does feel somewhat smoother.

[Mineria]

Originally Posted by HonoredShadow

How do you test if its enabled in windows?

From CMD: bcdedit /enum
One line should say: useplatformclock Yes

Althoug it seems to be more related to FSB overclocking.

Some motherboards/BIOSes dynamically varies the FSB
frequency depending on the processor's load, and this results in TSC
(Time Stamp Counter, the internal processors' clocks) not being longer
the reliable source of time, even if processor claims it is; and some
of Windows timer-related API becomes broken as the sequence.
Actually, this does not cause any real performance degradation,
however, just looking into outputs one can easily suppose that
there is serious performance degradation.

Ive seen a few mention that it fixes multimedia playback issues, and even IBM advices that it gets via bcdedit enabled for certain software/hardware combinations.

EDIT: Something for Windows 8 users:
bcdedit /set disabledynamictick yes
What it will do is stop Windows from coalescing CPU clock ticks when idle, a feature added in Windows 8 for power savings.

If you have real high DPC spikes your better of investigating which driver or software that causes it thou, since neither of the 2 settings above will help upon that.

[Mineria]

Originally Posted by kalston

Not exactly placebo.

When I enable it in windows and get 14.3 or so mhz in wintimertester my system feels completely different. It is smoother but everything is somewhat slower and delayed. The difference is very noticeable for me (and some other people have reported the same thing on neowin forums).

And regardless of the windows configuration enabling it or not in the bios makes a slight difference in terms of DPC latency (apparently windows uses different timers by default so disabling HPET in the bios means one less conflicting timer to use and lower DPC latency). However apart from the DPC latency readings I certainly can't tell the difference in benchmarks or games between HPET ON/OFF in the bios. It's only by enabling it in both windows and the bios that I notice a BIG (and NEGATIVE) difference. Why don't you just try it for yourself? It's harmless and easy to revert the changes.

What kind of motherboard are you using?
You should also check the output with this tool: http://www.resplendence.com/latencymon or with xperf: http://social.technet.microsoft.com/...2-cea920296271

[Prophet]

Originally Posted by Mineria

From CMD: bcdedit /enum
One line should say: useplatformclock Yes

Althoug it seems to be more related to FSB overclocking.

Ive seen a few mention that it fixes multimedia playback issues, and even IBM advices that it gets via bcdedit enabled for certain software/hardware combinations.

EDIT: Something for Windows 8 users:
bcdedit /set disabledynamictick yes
What it will do is stop Windows from coalescing CPU clock ticks when idle, a feature added in Windows 8 for power savings.

If you have real high DPC spikes your better of investigating which driver or software that causes it thou, since neither of the 2 settings above will help upon that.

http://www.sevenforums.com/general-d...e-command.html


bcdedit /set useplatformclock true (then reboot) is said to enable HPET using Win 7.

bcdedit /deletevalue useplatformclock (then reboot) is said to remove it.

So full credit goes to the guy on sevenforums.

[Mineria]

Originally Posted by Prophet

http://www.sevenforums.com/general-d...e-command.html


bcdedit /set useplatformclock true (then reboot) is said to enable HPET using Win 7.

bcdedit /deletevalue useplatformclock (then reboot) is said to remove it.

So full credit goes to the guy on sevenforums.

It will not enable it if it is disabled in your BIOS.
Quest was: How do you check if it is enabled on Windows, btw.
Where the command is: bcdedit /enum

[brendanvista]

If you run this tool and it says 14.xxxx mhz, then you have it enabled.
http://www.mediafire.com/?xzo9n84d8lze9nb
I just did this tweak; I'll do some testing and see how things go.

[Mufflore]

I tried this last night and it made very little difference for me, but I didnt have any issues with jerkiness or perfomance before this.
Before doing it, wintimertester reported my QueryperformanceFrequency as 3MHz, after it was 14MHz (to clarify that HPET is fully active and is the sole event timer).
I did a few benchmarks prior and afterwards, namely Heaven 2.5, Heaven 3.0 (both GPU limited), Crysis Warhead DX10 (GPU limited) and X3:TC benchmark (CPU limited).

Results:
All results were identical (within 1%) except X3:TC which dropped from 141fps to 131fps (7% drop).

Further observations:
During the loading of Crysis warhead, the grey loading map showed more frames on screen.
There is a lot more EM noise on my microphone socket on my Auzentech Prelude soundcard (used for listening to satellite TV through PC as I'm not using a pre-amp or audio switch), while running the benchmarks.

I dont doubt that some people will find it helps in an extreme circumstance, but not for me.
In fact it caused slightly lower framerate in the CPU limited test, although being CPU limited is not common with todays games.
I'll keep my eye on this.

If I dont see any further issues, I wont change back.

[spajdrik]

oww crap, i enabled it and since then windows was randomly freezing, i dont have settings in bios for that but i guess its permanently enabled and together with this registry parameter its a mess for system, ohh well.

[kakarot]

Don't see the option in my bios as well. Running that tool shows 4.09MHz and my dpc latency hovers around 102-138 depending on what I'm doing on the pc.

[HonoredShadow]

Originally Posted by Mufflore

I tried this last night and it made very little difference for me, but I didnt have any issues with jerkiness or perfomance before this.
Before doing it, wintimertester reported my QueryperformanceFrequency as 3MHz, after it was 14MHz (to clarify that HPET is fully active and is the sole event timer).
I did a few benchmarks prior and afterwards, namely Heaven 2.5, Heaven 3.0 (both GPU limited), Crysis Warhead DX10 (GPU limited) and X3:TC benchmark (CPU limited).

Results:
All results were identical (within 1%) except X3:TC which dropped from 141fps to 131fps (7% drop).

Further observations:
During the loading of Crysis warhead, the grey loading map showed more frames on screen.
There is a lot more EM noise on my microphone socket on my Auzentech Prelude soundcard (used for listening to satellite TV through PC as I'm not using a pre-amp or audio switch), while running the benchmarks.

I dont doubt that some people will find it helps in an extreme circumstance, but not for me.
In fact it caused slightly lower framerate in the CPU limited test, although being CPU limited is not common with todays games.
I'll keep my eye on this.

If I dont see any further issues, I wont change back.

Sorry I'm probably being thick but the later half of this. Is this with HPET on or off?

Thanks.

[Mufflore]

All is with HPET active.
I have left it on for now.

[Mufflore]

Originally Posted by spajdrik

oww crap, i enabled it and since then windows was randomly freezing, i dont have settings in bios for that but i guess its permanently enabled and together with this registry parameter its a mess for system, ohh well.

Its easy to disable again.