How much does the amount of cache impact in the performance of the emulator? For example, an Athlon x2 7850+ is normaly slower than a Athlon II x2 240 clock per clock, but but perhaps the shared 2MB of L3 cache in the 7850 does better in pcsx2 (without overclock).
Another question, does 1MB per core (AII x2 240) offers better performance than 1MB shared (E3200) in this emulator? I'm searching a super-cheap option for pcsx2 and Dolphin, and I just can't decide, please leave OC appart.
Sorry for my english, and thanks for reading.
10-05-2009, 07:53 AM
(This post was last modified: 10-05-2009, 08:03 AM by ellachen0417.)
I'm just basing this from experience, but I have just upgraded from an e5200 (45nm wolfdale, 2 MB cache) overclocked to 3 ghz to an e8400 (45 nm wolfdale, 6 mb cache) stock @ 3 ghz and didn't notice any significant speedup. From my memory, the OCed e5200 can run DBZ Infinite World at 64 to 70 fps when frame limit is turned off, while the e8400 runs it at around 64 to 72.
I'm not an expert so I'm not sure about this, but the speed difference could have been affected by something else aside from the cache size. Even if the e5200 was OCed, I still ran it at a slower FSB speed (quad pumped 200 mhz OCed to 240 X 12.5 = 3ghz) than the e8400 (quad pumped 333 mhz X 9.0 = 3ghz)
I'm basing this again from my experience, so I can't say anything about the Athlon cpu, but the E3200 (45 nm core @ 2.4 ghz, 1mb l2 cache) may not give decent consistent speeds with a lot of games on pcsx2, since I had to OC my e5200 before I got fullspeed in some of the less demanding games (dbz infinite world, which is a simple celshaded 3D fighter, runs @ 45-58 fps on stock and with native res and the emotion engine speedhacks enabled, FFX is fullspeed. Dolphin side is much easier as I get to play some of the more famous games at fullspeed, SSBM, not so much)
+ geforce GT 440 @ Win7 64bit
10-05-2009, 09:59 AM
(This post was last modified: 10-05-2009, 10:03 AM by Air.)
From PCSX2's perspective cache is pretty irrelevant. Really small caches (less than 1MB per core, like some of the older Athlons) probably could have a negative impact, though not a significant one. And very large caches (4mb+ per core) could help a wee bit. But anything in between is large enough to hold the core emulation VM states, and too small to hold anything else in the emulator.
The only part of the emulator which might benefit from various cache sizes is the GSdx software rasterizer, but even that is doubtful since the rasterizer has to render in tandem with the reception and processing of several megs of texture data per frame. So if it does benefit, it would be limited to only specific titles that do very little texture swizzling.
Edit: Most of the cache coding we do for PCSX2 is related to the L1 caches only (first level), which are typically 8 to 64kb per core. The size of the L1 cache can matter A LOT, so look at that value instead. A double-sized L1 cache could yield noticable speedups in *all* types of software.
Jake Stine (Air) - Programmer - PCSX2 Dev Team
Um...texture SWIZZLING? What in the world? That's the second most ridiculous tech term I've ever heard, coming second only to "dongle".
All PS2 textures stored in memory in very clever swizzled format's -- pixel blocks does not put in one-for-the-other order, but in complicated way, that allow very fast method of copying of half, quad, 1/8 or 1/16 part of texture (it's really important, in PC world big 100*100 texture stored in linear way require 25 memory copy operations to obtain part of this texture with size 25*25 -- it's slow). But henceforth, we all do unswizzle-swizzle in our GS plugions to often.
So looking at the L1 cache of both processors, the athlon II x2 "has" to offer a better performance in pcsx2 than the celeron dual core (64kB per core in the AMD one vs. 32kB per core in the Intel one).
I have 2 options, cpu upgrade of my current rig (e3200 @ 2916mhz on an asus p5gc-mx/1333, 243mhz fsb hole and no bsel mod possible with it), or sell my rig and build a totaly new one (a cheap one) with a 240 and a biostar mcp6p m2+ (it's am3 ready, no 2GHz HT but who cares, it's ultra cheap, can oc up to 310MHz of fsb and can tweak cpu, ram and nb voltage, something my current motherboard can't do).
Thanks for all your help. I think selling my pc is the best option, the 240 @ 3600-3800mhz can be very good in pcsx2 and dolphin (I hope). Oh and sorry for my bad english.
The i7 has only 32kb of l1 cache, while AMD processors have 64kb so even then the cache seems to not matter compared to lots of other things.
Intel CPUs have a smarter L1 cache prefetch and coloring algorithm, that typically makes the L1 cache about 33% more effective than AMD's cache. So yeah you can't really compare AMD/Intel cache sizes. You can compare Intel to Intel, or AMD to AMD, but not cross-chip.
Jake Stine (Air) - Programmer - PCSX2 Dev Team