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[Akio]

I know the difference. What I said is not incorrect. It can use 4 or more threads and it can utilize 4 or more cores. They are not mutually exclusive.

[karasuhebi]

It's not necessarily true that using 3 extra rendering threads will hurt the performance if MTVU is enabled. It depends on the load on each core.

If you enable MTVU and use 3 extra rendering threads, PCSX2 will use 7 threads.

Wouldn't that hurt performance though? PCSX2 is trying to use 7 threads on a CPU with 4 threads.

I know the difference. What I said is not incorrect. It can use 4 or more threads and it can utilize 4 or more cores. They are not mutually exclusive.

I wasn't implying you didn't know the difference, from all the posts I've seen of yours in this forum I know you're intelligent and well informed. All I was saying was that technically speaking, it lets you use more threads. It's an important distinction to make because some people might think you can only use the extra rendering threads option with a quad-core processor or better with how you worded it.

[Akio]

Wouldn't that hurt performance though? PCSX2 is trying to use 7 threads on a CPU with 4 threads.

It depends on the load on each core. For example, if PCSX2 uses 4 threads on a quad-core CPU that supports 4 threads and the load on the core that a software rendering thread is running on is 100% whereas the load on the other cores is 50%, running 3 more software rendering threads should improve the performance. On the other hand, if the load on each core is 90-100%, running 3 more software rendering threads will most likely hurt the performance.

[dogen]

Wouldn't that hurt performance though? PCSX2 is trying to use 7 threads on a CPU with 4 threads.

Not necessarily on a modern processor.
Look at how many execution units haswell has per core.



I run mtvu in most games on my dual core for a speedup, and in software mode I usually use 2 or 3 extra threads.

[Blyss Sarania]

It all comes down to whether or not the "shared" threads are maxing out their respective cores. Consider MTVU and EE sharing a core. If the EE is needing 50% and the VU 40%, then it will be a speed up. But if the EE needs the whole core and VU needs 40%, then slowdown.

[dabore]

you can't even pin that load per percent. that diagram goes down to the instruction level. this' how it really hyperthreads. single clockcycle. if one thread uses a integer instruction another thread can use the floating point registers at the same time. the EE is integer with mixed code on the fpu. the vu macro code possible with simd. the VU emulation needs an integer unit too to address and the simd floating point units to execute. if both or more running on one core it can overlap and slow it down to "instruction stalls". that hyperthreads however it hyperthreads. sure both gain and the "stall loss" is possible if overdone.

[karasuhebi]

So basically what you guys are saying is there's no right number you can set the extra rendering threads at on a given CPU. It varies depending on how PCSX2 is using the cores. Great. -_-

[dabore]

nah. how many benchmark threads we had? generally you can add as many extra as hw threads you have - 2. sometimes you can add 1 more. it depends on the game. a lil bit. it's trial and error. whether get fps or not. so...

[karasuhebi]

So either total threads - 3 or total threads -2, nothing higher than that, right?

[Blyss Sarania]

So either total threads - 3 or total threads -2, nothing higher than that, right?

Not necessarily, but that's generally what I recommend. It's the most effective way without testing many combinations. In my PCSX2 FAQ I break it down like this:

Dual Core CPU: It won't help with one of these unfortunately, unless you have Hyperthreading, in which case you might try 1 or 2
Quad Core CPU: 2-3 extra threads is best, unless your CPU has Hyperthreading, in which case 4 or 5 MIGHT be useful.
Hex Core CPU: 3-4 extra threads
Octa Core CPU: 4-5 threads

Which is a good guideline.