It seems that on an i7 mobile Dolphin only uses 25% CPU power.
Dolphin says I have 16 cores. HT gives me 8. I can't disable HT in bios.
It would appear that it is using 2 cores (dual-core enabled), but only at about 50% (i.e. 50% in 4/8 cores). It will stick at 25% and go no higher, so I suspect it is not actually using 2 physical cores.
Has there been any additional info or resolution to this issue? The i7 mobile I have is a 1.6ghz (2.8? speedstep?) and I really need that other core..
Do you have lock threads to cores on or off?
I heard to NOT use that option with HT..
Just tried it, it didn't change the overall speed/CPU Usage, but appears to have given me 2/8 cores at 100% instead of 4/8 at 50%.
As far as I know, intel cpu's or at least i7's spread the load over all the cores, by constantly changing between the cores. This is a good thing. Lock threads to cores assigns one core for cpu, and one for gpu in dolphin. Overall setting this option to 'true' slows down your performance in dolphin significantly.
For Dolphin, it only can spread the load out over the "fake" core for the real core (Hyperthreading), it can't spread Dolphin's load out over another actual physical core. If you use Lock Threads to Cores, it uses one real and one fake (I think they are called physical and logical) core instead of two real and the two paired fake HT cores instead of two real cores, effectively only actually using one core. Dual Core assigns one core for cpu and one for gpu, via Dolphin programming. The way that a complex hardware emulator like this works, the processor/OS can't go playing around with the threads much, they are hard coded to cores, that's the way it has to be.
That is a simplistic answer that will probably be corrected.
I would correct both of you by explaining it but I really don't really like writing a long post right now. You can use the search field to find some of my other posts where I have explained it (which I have done at least 7 times by now). All you really need to know is that you should have lock threads to cores off if your cpu uses HT. Anyways with lock threads to cores off on an 8 thread i7 you should be getting 25% load.
(12-10-2010, 02:11 PM)NaturalViolence Wrote: [ -> ]I would correct both of you by explaining it but I really don't really like writing a long post right now. You can use the search field to find some of my other posts where I have explained it (which I have done at least 7 times by now). All you really need to know is that you should have lock threads to cores off if your cpu uses HT. Anyways with lock threads to cores off on an 8 thread i7 you should be getting 25% load.
^ Can you please point me to a post explaining why it's 25% and not 50%, I'd appreciate it.
2 threads = 100% (since dolphin uses 2 threads)
therefore
4 threads = 50% (since dolphin uses 2 threads, which is half of the number available)
therefore
8 threads = 25% (since dolphin uses 2 threads, which is 1/4th the number available)
It is simple math really. I don't believe HT changes this since the os has no way of knowing how many physical threads their are, it only knows how many logical threads their are therefore it can't distinguish between the two. I could be wrong but I am fairly certain HT does not change this, or order to change this the os would have to know the number of physical threads, not just logical threads.
Well HT does change it as there wouldn't be 8 threads or non-physical threads without it? And it would appear that the load gets spread over 4 of the 8 threads at about 50% CPU somehow if lock threads to cores is not on, if it is on it uses 2 threads at max CPU. Either HT is the problem, there is something weird with the CPU otherwise, or there is a problem with Dolphin, because with Dual Core on it should be able to use more than a cap of 25% CPU. IIRC PCSX2 had the same issue, but didn't have speed issues so it didn't really matter, I really think HT is the problem here.
I wish I could turn HT off, HP doesn't seem to care to give a decent BIOS
Interesting.. the 32-bit Dolphin 2.0 uses ~35% CPU.. but it's much slower!