Does HPET on *actually* decrease stuttering?

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eBombzor
Posts: 2
Joined: 26 Jan 2015, 18:54

Does HPET on *actually* decrease stuttering?

Post by eBombzor » 13 Aug 2019, 23:21

"Most systems already have high precision clocks (HPET, TSC, etc). However, if you intentionally manually disabled this setting in your BIOS, turn it back on. High-precision clocks are needed for microsecond-accurate stutter-free frame rate capping."

https://www.blurbusters.com/howto-low-lag-vsync-on/

Has anyone tested or can attest to this claim? From some casual personal testing I do not see a difference in the graph for frame times between those two options. However, HPET off greatly helps with reducing input lag so I've had HPET off ever since I discovered this setting.

Has anyone experience HPET on reducing micro stuttering?

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Chief Blur Buster
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Posts: 6485
Joined: 05 Dec 2013, 15:44

Re: Does HPET on *actually* decrease stuttering?

Post by Chief Blur Buster » 16 Aug 2019, 17:17

eBombzor wrote:"Most systems already have high precision clocks (HPET, TSC, etc). However, if you intentionally manually disabled this setting in your BIOS, turn it back on. High-precision clocks are needed for microsecond-accurate stutter-free frame rate capping."

https://www.blurbusters.com/howto-low-lag-vsync-on/

Has anyone tested or can attest to this claim? From some casual personal testing I do not see a difference in the graph for frame times between those two options. However, HPET off greatly helps with reducing input lag so I've had HPET off ever since I discovered this setting.

Has anyone experience HPET on reducing micro stuttering?
Pandora Box #1

Older high precision clocks had problems that can make things worse. This of course, includes HPET implementations. So yes, turn HPET off if it is causing problems on your specific system.

However, most new systems have great high precision clocks that are already on by default (stuff better than the old HPET stuff).

___

Pandora Box #2

Also, consider latency average versus latency consistency. Some people prefer slightly higher latency as long as it's glassfloor nearly non-volatile latency. (Picture a preference, for say, a glassfloor consistent 8ms lag, instead of a highly volatile 2ms-7ms lag -- by having predictable lag, it's sometimes easier to aim preemptively / predictively). High precision clocks helps with lag consistency on some systems.

Then again, some methods such as RTSS Scanline Sync (different technique than low-lag VSYNC) uses precision busywaits instead of high precision events, and can bypass the need for for HPET.

(Absolute lag versus lag consistency is yet another second Pandora Box, too)
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