HyperThreading - My Take

[btacon 1,772]

Long story short.  I've got an old i72600k 16 gb memory, sata ssd drives and a NVIDIA 1070 / 8gb.  I've been flight simming for well over 20 years and old timers on this board will recognize my name as a long time member.  I mostly lurk now a days.

So back to my story, like most of you I'm always looking for that magic bullet that will speed up frame rate AND stop the stutters.  New drivers, new configs, all sorts of voodoo in the quest of better performance, and I like many of you have tried them all, except one up to now.

So after my son bought an i5 9600k 6 cores, no HT, Highly Recommended for Gaming by other Gamers ($200.00 US) I started to read the game threads and they have all sorts of common wisdom as to why HT (Hyperthreading) or "Ghost Cores": are a bad BAD idea for gaming.  I've seen the same discussion myself here for many many years.  HT, Yes or No?  I've seen two camps and there was some "heat and friction" from both sides so I just figured that I would leave well enough alone and leave the HT On/Off switch in the bios alone...until 3 days ago.

I went in, turned off HT in bios.  Restarted.  Computer came right up.  Started P3dv4.5 in my default startup  It came right up and the first thing I noticed was my avg. fps on Rwy engines running had come up by 7 to 10 percent (2-3 fps).  Then I took off and started yanking the plane around the pattern and the first thing I noticed was, "Smoother...smoother frames, smoother response to stick, smoother..."  And it remains so to this day.  Best investment I've made in a long time and it cost me NOTHING.

True story.  YMMV  You cant hurt a thing and you can put it back with one reboot if you don't like it.

-Braun

[ray hughes 165]

Thanks for posting your experience. Hyperthreading has indeed been a hot topic on and off in this forum. I have tried both,  but am happy to turn my hyperthreading off again with the new Nvidia drivers and latest system updates and give it another try.

[joby33y 152]

Like you, I’ve been simming for a lot of years.  I built a lot of PC’s over the years, keeping up with each release of MSFS & now P3D.  My latest rig is an 8700k and I have tested hyper threading ON and OFF extensively with many scenarios in P3D v 4.x, always looking for the magic ‘voodoo’, reading all the threads on this forum.  But I can definitively agree with you, HT OFF results in much smoother performance on this rig. I also take it a step further and use a tool to move (mask) other processes to ensure no one single ‘core’ is overloaded or near max when P3D is running.  This results in very smooth performance....usually  😉

What I’ve learned from reading all the posts, is that it seems to be machine / CPU specific.  I’ll upgrade HW next year, for v5 or FS20 or whatever, and then I’ll test it again, & might have better performance w/ HT ‘on’.   

Thanks for posting!  Blue skies, 

[gsand 105]

8700k here , tried with and without HT and it's definitely HT off for me. One thing I did was open Task manager during a couple of sessions and took a look occasionally to see what cores were used the most. Heavy loads all are used although I do see a definite trend for my P3D to use 0, 2 and 5 the most. 4 was the lowest always so I've got RealTime, AS and ASCA all parked on 4. It seems to make a difference. YMMV...😉

[Wise87 1,275]

19 minutes ago, gsand said:

4 was the lowest always so I've got RealTime, AS and ASCA all parked on 4. It seems to make a difference. YMMV...😉

How do you do that? Never mind, I found out how to. Im going to try it tonight. 

Edited November 4, 2019 by TalonMX

[jimimac 19]

My cpu was running at 4.6 if I o/c to 4.8 after a few minutes the temps would go really high and I would get throttling I turned off ht and was able to o/c back up to 4.8 what a difference runs really smooth in vr with active sky  pmdg 737  I only have orbx global installed I deleted my other orbx sceneries England Norway Scotland and wales also Lc Europe but still use some orbx airports.

[AnkH 2,233]

Although there are still people having different experience, I always get the best results out of my sim (was like that for FSX, P3Dv3 and now P3Dv4) with mimicking "HT off" by using an affinity mask entry doing this (01 01 01 01 01 01 or "1365" in my case).

Advantage: you do not have to manually switch HT off and you can still use HT for the other things you do with your rig. Of course, if you use your rig exclusively for simming, turning HT off in the BIOS might be the easier approach. But then, honestly, why buying a processor capable of HT?

Then, as @gsand said, moving as much addons running along P3D off core0 does wonders. I achieved this by using batch files for REX, ActiveSky and ProATC/X. Overall, my simming was never better than in those days. Almost always smooth, reasonable FPS, pretty high settings and almost no troubles.

[Michael Moe 494]

22 minutes ago, AnkH said:

Although there are still people having different experience, I always get the best results out of my sim (was like that for FSX, P3Dv3 and now P3Dv4) with mimicking "HT off" by using an affinity mask entry doing this (01 01 01 01 01 01 or "1365" in my case).

Advantage: you do not have to manually switch HT off and you can still use HT for the other things you do with your rig. Of course, if you use your rig exclusively for simming, turning HT off in the BIOS might be the easier approach. But then, honestly, why buying a processor capable of HT?

Then, as @gsand said, moving as much addons running along P3D off core0 does wonders. I achieved this by using batch files for REX, ActiveSky and ProATC/X. Overall, my simming was never better than in those days. Almost always smooth, reasonable FPS, pretty high settings and almost no troubles.

+1 , I use Process Lasso which saves the settings on reboot of PC so i dont have to make the CPU choices everytime.

Some people seems to have a problem with this software but i really havent noticed anything.

Michael Moe  

[Rocky_53 1,566]

I did excatly the same Braun. It was immediately apparent that although there was no gain in fps, the sim was far smoother with HT off and no AM setting of any kind in the cfg.

[F737MAX 5,530]

A CPU upgrade meant I could no longer use Process Lasso, so I'm now using Prio Priority Saver. A once-off 'set and forget' of the processor affinities in Windows Task Manager, means no need for batch files, affinity mask in P3D.cfg, or turning HT / SMT off.

Using the program, I have the equivalent of an affinity mask for P3D running on the first logical processors of each core. I've shunted all other programs away onto lesser used threads.

CPU heat is acceptable at a maximum 77°C when I push all the settings to very high / ultra, and the only stuttering happens (briefly) when too much AI generates when I fly into range of a big airport (I have 650 AIG AI airlines installed and running at 100% because seeing every flight and full airports is my weakness).

Very happy to have found this solution as I get the best of both worlds, SMT on for daily tasks and a smooth P3D experience.

[swiesma 625]

HT off on my 6700K 4-core Oldie results in massive Blurries.

[joepoway 241]

3 hours ago, F737NG said:

A CPU upgrade meant I could no longer use Process Lasso, so I'm now using Prio Priority Saver. A once-off 'set and forget' of the processor affinities in Windows Task Manager, means no need for batch files, affinity mask in P3D.cfg, or turning HT / SMT off.

Using the program, I have the equivalent of an affinity mask for P3D running on the first logical processors of each core. I've shunted all other programs away onto lesser used threads.

CPU heat is acceptable at a maximum 77°C when I push all the settings to very high / ultra, and the only stuttering happens (briefly) when too much AI generates when I fly into range of a big airport (I have 650 AIG AI airlines installed and running at 100% because seeing every flight and full airports is my weakness).

Very happy to have found this solution as I get the best of both worlds, SMT on for daily tasks and a smooth P3D experience.

What CPU upgrade did you do that prevented Process Lasso to be used? I’m about to fire up my new i9-9900KS build today.

Joe

Edited November 6, 2019 by joepoway

[F737MAX 5,530]

16 minutes ago, joepoway said:

What CPU upgrade did you do that prevented Process Lasso to be used? I’m about to fire up my new i9-9900KS build today.

AMD Ryzen 1700X to 3700X. Had stability issues as the new CPU didn't want to play nicely with PL.
Hopefully, you don't have any problems when using PL.

Enjoy the KS, fingers crossed you have a golden chip for 5.2 GHz all-core.
 

[mikeymike 357]

I have just switched mine off on my i9 9900k

and I must say it’ll the sim is smoother.

 

[Rocky_53 1,566]

2 hours ago, swiesma said:

HT off on my 6700K 4-core Oldie results in massive Blurries.

Bizarre. I have the same CPU and have experienced the exact opposite following exhaustive testing.