Hyperthreading

[SteveW 1,792]

Does P3D benefit from HT?

 

Indirectly. With HT enabled the overall performance of the PC rises.

 

However with HT enabled, beware that a MT app like P3D or FSX will simply spawn threads for the jobscheduler to place onto available LPs. It is a problem for P3D or FSX if the main thread shares a core with the next sim thread, to the tune of maybe around 8% lost to the sharing of the core with the second thread spawned. This happens because the second thread starts before the first thread is fully maxed, and the jobscheduler sees the next LP as little used. So we use an AM to mask an LP of the first core, say for 8LPs we can use an AM=254=(11,11,11,10) or 253=(11,11,11,01) which ensures the second thread starts on the second core.

[Peter Webber 339]

Steve, as I have mentioned previously, I have used your advice with great success....you are an authority regarding this topic. Thanks for your continued support within Avsim forums. I'm sure many agree !

[WebMaximus 372]

I fully agree, Steve's knowledge and his willingness to share it with all of us is highly appreciated!

 

Will try and play around with HT ON and OFF to see what will give me the best result.

[SteveW 1,792]

Thanks guys, I appreciate the mention!

 

 

So does P3D benefit from HT? Yes, but indirectly, and with the possibility of problems.

 

With HT enabled the overall performance of the PC rises.

 

However, with HT enabled beware that a MT app like P3D or FSX will simply spawn threads the jobscheduler places onto available LPs. It is a problem for P3D or FSX if the main thread shares a core with the next sim thread, to the tune of maybe around 8% or more lost to the sharing of the core throughput with the second thread spawned. This happens because the second thread starts before the first thread is fully maxed, and the jobscheduler sees the next LP as little used. So we use an AM to mask an LP of the first core, say for 8LPs (4 core HT=On) we can use an AM=254=(11,11,11,10) or 253=(11,11,11,01) which ensures the second thread starts on the second core.

 

We have to remember when we apply an AM to a app, other processes started by that app exist in the same AM (unless they purposely affect the outcome). If we apply AMs for other software, ensure to allow at least two LPs or cores, else thy can become blocked with their own supporting resources.

[supersym 52]

Finally,  let me know if Im OK : With a 6 core AM = 4094 ?  (1111 1111 1110)  

[WebMaximus 372]

Looks good to me, you masked the first LP.