500MB VAS reduction and increase FPS by 22% in V3 ... need some testers

[Mickeyj 35]

Hi MJ,

 

Thanks for testing ... it's a little odd that you started with with much higher VAS usage with HT OFF but ended up with less VAS usage overall with HT OFF vs. HT ON.  Did you do any view changes/panning just before data logging?

 

What I typically do is two full 360 view rotations in VC and then got to Spot mode and do another two 360 rotations around aircraft (slow rotations) to ensure textures get loaded ... then start VAS logging.

 

 

G' day Rob,

 

i didnt do a full 360 neither in VC nor in spot view. Just to mention i used 60Hz refresh rate on my beamer and unlimited frames in sim. Going for 30HZ seems to smooth things out. I dont know where the low VAS came from. What im doing now is testing Steves suggestion with AM=30. It actually gives a few frames more. However i have the impression that it causes very light stuttering. I also added the "FIBER_FRAME_TIME_FRACTION=n"  With value of 0.015 i gained another 3-5 frames. Going down to 0.00 all buildings are removed by the sim itself -didnt know that one With 0.33 it seems ok but only with the in-sim framerate limiter set to 30 or 33. VAS seems to be ok for me. I usually dont fly the big n heavy ones. Made a flight from orbx KEKA to orbx KSTS over NCA yesterday no VAS problems here. Will do another flight over PNW from orbx KBVS to FSDT CYVR in Carenados new 406. I will let FSUIPC do its logging. I´ll report back.

[Manny 1,293]

G´day Rob,

 

as promissed her are my test results. I also tried AM=1364 based on this calculator http://www.gatwick-fsg.org.uk/affinitymask.aspx?SubMenuItem=hardware

Results were similar to HT OFF

 

Test machine:

 

Intel i7 5820k oc´ed 4.5GHz +++ ASUS Rampage Extreme V MoBo +++ GTX 980 SLI +++ 16GB Ram +++ Win 64 bit PRO dedicated SSD +++ P3Dv3 dedicated SSD

 

 

 

How do you get to display the CPU usage on the sim screen?

[swiesma 625]

I switched off HT yesterday and during the first test flight I got a CTD and in the Eventviewer it says something about ntdll.dll.

But I guess this was only coincidence. Didn't have time to do more testing yesterday.

[Mickeyj 35]

How do you get to display the CPU usage on the sim screen?

 

Hello Manny,

 

that is the GPU status not the CPU status. There is an app called PrecisionX by EVGA it is an GPU control and monitoring app. http://de.evga.com/precision/

[DutchAir 2]

I seems to me that this post by SteveW fully explains the observation made by Rob and others pointing out the low VAS usage and higher FPS with HT=off with no AF compared to HT=on with no affinity Mask.

 

He explains that VAS usage is Higher with more threads running made possible by HT.

He also explains that without an affinity mask with HT on the first two P3D threads started will both be running on the same physical processor whereas with HT=off the first two threads started will be on separate physical processor, thus explaining the better performance with HT=off and No AF v's HT=on and No AF

 

So the real question is which delivers better performance on your system? HT=off and no AF or HT=on and AF=x where X is determined by your particular CPU and the other applications you are running at the same time as P3D.

If we don't limit the number of threads the sim starts-up, then our available VAS will be eaten, several megabytes per thread, and even more when we run a 32bit thread on WOW64.

Enabling HT on an 8 core CPU gives 16 LPs (logical processors), without an AM there would be too many threads, and since these have to synchronize with the main thread there will be more stopping and synching data with the main thread.

Also when we enable HT we must know that the Jobscheduler will allocate each thread the next available LP. On an HT enabled system, and no AM, the first two Sim threads will start up on LP0 and LP1, both on core 0. SO with HT enabled we must also mask one of the first LPs.

With HT disabled we need only limit the number of cores and with a 4 core CPU we need do nothing.


With HT enabled, a large part of circuitry comes into operation to make two threads swapped on a core not run with the penalty of stopping, reloading registers, and restarting alternate threads. So up to half the time the CPU does this is saved. That's why the CPU get's hotter, it's doing more work funnily enough.

With HT enabled the PC performance overall is increased, but with certain designs of multi-threaded software like FSX and P3D, we need to help the Jobscheduler by masking one LP of the first core encountered, and limiting the total number of main threads.

Adding an AM reduces the number of available LPs to the system threads invoked by the main sim threads running. The sim spawns upward of 40 threads and these run in the affinity of the application.

Simply put, with HT enabled the sim performance will suffer without an AM since it will share the first available core with a second main thread, hence we mask one of the first LPs. Also with or without HT enabled, if we have too many LPs we'll run into the problem of VAS lost and too much synching with the main thread.

When pushing an overclock we can save heat with HT disabled, and we can gain a few more fps since the main thread will run faster, but we will lose some overall performance in the PC since the I/O and networking is highly threaded.

 

[SteveW 1,792]

I seems to me that this post by SteveW fully explains the observation made by Rob and others pointing out the low VAS usage and higher FPS with HT=off with no AF compared to HT=on with no affinity Mask.

 

He explains that VAS usage is Higher with more threads running made possible by HT.

He also explains that without an affinity mask with HT on the first two P3D threads started will both be running on the same physical processor whereas with HT=off the first two threads started will be on separate physical processor, thus explaining the better performance with HT=off and No AF v's HT=on and No AF

 

So the real question is which delivers better performance on your system? HT=off and no AF or HT=on and AF=x where X is determined by your particular CPU and the other applications you are running at the same time as P3D.

Depends on how you define performance. In terms of raw fps delivery, there should be no difference between HT=Off and HT=On with a proper mask. But the bit of extra overall system throughput with HT=On may benefit the smoothness of the sim. Overclockers find more raw fps with less heat generated by HT=Off and higher GHz.

 

..in fact overall it's possible that HT=On can produce higher average raw fps than with HT=Off at the same clock. Since sooner or later the core hosting the main thread will be shared with some other thread, that alone is less efficient than on an HT core. In the image of the 6 core with HT=On I posted earlier, in the top half with the affinity mask applied, LP 7 is barely affected when another application starts around 2/3 into the graph. The jobscheduler works out to move the task onto other cores more efficiently with HT enabled. The task blip can be seen appear across the chip on other cores, only a little appeared on core 3, allowing LP 6 to continue less interrupted - have a look. With HT enabled, if the CPU is interrupted, the performance will be better contained than with HT=Off.

[Richard Sennett 2,499]

enabled, if the CPU is interrupted, the performance will be better contained than with HT=Off.

 

1+

[Mickeyj 35]

Hello Steve,

 

i tried your observation on my system, i7 5820k @ 4.6GHz. The HT off + AM=30 introduces stutters. Without AM everything ws back normal and smooth. Its fun playing around and tweaking which imho is not required as the sim runs great anyway

[SteveW 1,792]

 

 

Hello Steve,

 

i tried your observation on my system, i7 5820k @ 4.6GHz. The HT off + AM=30 introduces stutters. Without AM everything ws back normal and smooth. Its fun playing around and tweaking which imho is not required as the sim runs great anyway

But that was for demonstration purposes only to see the effect on VAS, not a recommended setting. See my other posts for recommendations.

 

It would help if you had some grasp of the discussion MickeyJ, I've mentioned several times to use no jobscheduler section with HT disabled - sorry.

[Bob Scott 7,720]

Hello Manny,

 

that is the GPU status not the CPU status. There is an app called PrecisionX by EVGA it is an GPU control and monitoring app. http://de.evga.com/precision/

 And one more useful tidbit on eVGA precision--if you have a keyboard or game controller with a display (I use a Logitech G13 for view control) you can set it up to display GPU stats on your controller.  Very handy.

 

Regards

[WayneG 1]

I just did a flight in the 777 from Heathrow to Nassau MYNN the new aerosoft scenery. I have a i4790K with a Z97 Pro 4 Motherboard, now at the time i had HT on and while i was on approach i OOM. Now my settings are not really high. So i think what i will do is do a flight from Miami with HT off and go to MYNN and see what happens and i will report back on my findings.

 

Wayne George

[Clutch Cargo 384]

So, after 3 months and 6 pages of posts is there a definitive answer on this?

[Skywolf 992]

I have a i7-5820K.

 

There is 100% increase in VAS when I use 5 or 6 Cores (I have HT off in the Bios).  I have to lock the sim in 4 Cores using Affinity Mask to have some free VAS.  This could be cpu dependent or the fact I am also in SLI system.  Can't understand why some are not affected by it.

 

Will post my settings later today.

[virtualstuff 758]

So, after 3 months and 6 pages of posts is there a definitive answer on this?

 

Nope because I don't have the issue with HT on ;-) and it will stay on local lol with V3.1