Phenom/Barcelona L3 Disabled Benchmarks?

[praeses]

Has anyone managed to find any benchmarks of a Phenom or Barcelona compared to the same configuration with the L3 cache disabled? I'm really curious what sort of performance benefit if any is provided in real world applications, more so in the gaming/encoding and perhaps maya. This is mostly just to fulfil my curiousity as I mentionned but as this thought has been hounding me for awhile.

 

[DrMrLordX]

I asked about this and got a comment that there's a 10% reduction in performance according to Fudzilla, though I can not find confirmation of this fact. Seems a bit off to me.

 

[praeses]

Seems peculiar to me as well. As I recall most of the K8 chips did not benefit greatly from L2 cache due to the low latency/high bandwidth hypertransport bus & integrated memory controller. I figured that being on the same die,using the same bus alone they would scale quite well without the addition of shared cache. The X2's and Opteron's the opteron x65+ proved that.

I'm just thinking that once the "errata" is fixed and a few steppings roll out, it may make more sense to drop the L3 for the desktop chips and have them run just a hair faster. A Phenom with no (not disabled, but inexistant) L3 cache should be fairly cheap to produce after all the engineering has taken place and draw ever so slightly less power. I cant remember exactly how much power sram draws alone, but wasn't it like 5-10 watts/meg in the prescott days @ 3ghz? I'ld imagine it should be ~ 10watts for the phenom. I could be way off here, google/forum/article search isn't being my friend today. Of course, less cache could reduce the effective instructions/clock if it is really being utilized. Maybe I'm just thinking its a conspiracy.

 

[DrMrLordX]

In the short term, I believe the TLB bug can be sidestepped by disabling the L3 cache, which is further incentive to figuring out how much performance is lost when Phenom is run without L3 enabled.

 

[praeses]

You would almost think that people would be trying that with their current Phenoms and reporting the impact. Currently I cant get my hands on one to test it out. Even if I could, I'ld have to buy another motherboard/ram to support it. A 2.4ghz Phenom for $200 w/no L3 may not just be my dream. Dont get me wrong, I currently recommend Core2s to anyone who asks, but the little fanaticism inside me is hoping for a good midrange AMD solution as they have provided many times in the past 7 or so years.

 

[DrMrLordX]

I'd like to play with a Phenom (and disabled its L3 in BIOS, at least to test it), but I have no idea if my AM2 board will ever support it. Abit isn't making any noises to the effect that they will support it via BIOS update . . . so it works as-is or it doesn't.

 

[AlabamaCajun]

I've got one on the way, but yes the mobo issue is the dangling what if. I should have the little marvel in my hands by Tuesday. I have email into ECS to find out if any current boards will run it but the L3 will not be visible on my BIOS which assuming it posts then the L3 would be always active. I'll try and post as soon as I can find out.