Microstutters with Hyper Threading on.

[keef]

I have been having a problem with games having a constant video stutter even with them emulating at 100% or higher. Kirby's Return to Dream Land was one of the most apparent, and after doing a lot of fiddling with all the settings to no avail, I finally decided to try some bios tweaking. Long story short, I decided to try turning off hyper threading, and after continuous testing and turning it back on again it is obviously the culprit.

I searched the forums and could find nothing mentioning HT being an issue but did run across other threads about stuttering. Is this a know issue?

[KHg8m3r]

Have you overclocked your CPU? I don't know how demanding this game is on the CPU, but you may be hitting a CPU bottleneck that can be remedied by overclocking.

Under Power Management for Windows, are you set to High Performance?

I do know that I had to reduce the IR and AA/AF from what I usually use as defaults. Did you try bringing down the IR/AA/AF a little bit to see if you were getting GPU bottlenecking?

[keef]

Yeah I tried all those things and much more. Maybe I wasn't very clear, but basically my problem was completely solved by turning hyper threading off.

Just wondering if this is a common issue because I'd rather have HT turned on, as emulation speed drops a bit in some games when it's off.

[Gir]

Hyperthreading is the bottleneck since Dolphin relies on single-threaded performance

two threads running in the same core are competing for the same resources. If each of the two threads gets only half the amount of a limiting resource then it will run at half speed, and the advantage of hyperthreading is completely gone. Two threads running at half speed is certainly not better than a single thread running at full speed.

[keef]

Interesting. So then the only fix is to turn it off? Considering that some games run considerably faster with HT on, that is a bit disappointing.

Also, if this is a known issue, why isn't it stated in an faq or something? I went through a lot to figure it out.

[Gir]

Interesting. So then the only fix is to turn it off? Considering that some games run considerably faster with HT on, that is a bit disappointing.

Also, if this is a known issue, why isn't it stated in an faq or something? I went through a lot to figure it out.

You will find majority of games will run better with HT off since games rarely take advantage of more then 2 cores, HT also causes stuttering in Battlefield 4.

[keef]

Kind of makes an i7 useless then huh? I guess I should have gotten an i5 instead and saved some money.

Thanks for the responses Gir.

[AnyOldName3]

HT helps in things like video editing and rendering, but it isn't really something most consumers will benefit from. You're right that an i5 would have been a better choice for gaming and emulation.

[keef]

Ah, I finally pinpointed the problem and thought I'd share. In the bios are two settings. "CPU C3 Report" and "CPU C6 Report". By simply turning off both, I can now leave hyperthreading on with no issues.

There is no discernible difference between having HT on or off, performance wise. Another thing that was necessary for smoothness was to turn on vsync in Dolphin.

[AnyOldName3]

Aren't C3 and C6 sleep states? They shouldn't be used when something demanding like Dolphin is running... unless the idle cores were being put to sleep, and then when Windows moved threads to them to minimise heating etc. they took a little while to get back to load clocks, causing stuttering.