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Cache and Memory Performance

I mentioned earlier that cache latencies are higher in order to accommodate the larger caches (8MB L2 + 8MB L3) as well as the high frequency design. We turned to our old friend cachemem to measure these latencies in clocks:

Cache/Memory Latency Comparison
  L1 L2 L3 Main Memory
AMD FX-8150 (3.6GHz) 4 21 65 195
AMD Phenom II X4 975 BE (3.6GHz) 3 15 59 182
AMD Phenom II X6 1100T (3.3GHz) 3 14 55 157
Intel Core i5 2500K (3.3GHz) 4 11 25 148

Cache latencies are up significantly across the board, which is to be expected given the increase in pipeline depth as well as cache size. But is Bulldozer able to overcome the increase through higher clocks? To find out we have to convert latency in clocks to latency in nanoseconds:

Memory Latency

We disable turbo in order to get predictable clock speeds, which lets us accurately calculate memory latency in ns. The FX-8150 at 3.6GHz has a longer trip down memory lane than its predecessor, also at 3.6GHz. The higher latency caches play a role in this as they are necessary to help drive AMD's frequency up. What happens if we turn turbo on and peg the FX-8150 at 3.9GHz? Memory latency goes down. Bulldozer still isn't able to get to main memory as quickly as Sandy Bridge, but thanks to Turbo Core it's able to do so better than the outgoing Phenom II.

L3 Cache Latency

L3 access latency is effectively a wash compared to the Phenom II thanks to the higher clock speeds enabled by Turbo Core. Latencies haven't really improved though, and Bulldozer has a long way to go before it reaches Sandy Bridge access latencies.

The Impact of Bulldozer's Pipeline Windows 7 Application Performance
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  • Elric42 - Thursday, December 01, 2011 - link

    I wanted to say one thing i dont have one but a friend of mine does and he showed me somthing my i5 cant do he was playing a game called crissis if thats how u spell it and running a video editting program at he same time well i cant do that with my i5 if i did the game would start to lag crissis takes alot out of your cpu bad programing even video cards have trouble with the game but bd seems to muti task better then what my i5 can do just wondering if its more for peeps who do alot of stuff at one time. Reply
  • ZyferXY - Monday, January 02, 2012 - link

    Thanks for pointing that out because not so long ago i saw a video on amd's web site where they were showing of a amd Llano notebook vs a intel sandy bridge core i7 notebook they started the same benchmark on both notebooks and the intel was quite fast but as they open more and more programs at the same time the intel starts to drop in performance where the amd is running stable. So my suggestion would be to run all benchmark on the bulldozer and i7 2600k again but this time open about 10 or 20 other programs a the same time then u will truly see the bulldozer shine. I am not a amd fanboy my current build a intel Pentium G860 and i am very dissapointed in myself i shouldve gone with the amd q640 it was around the same price when i bought it. My next build will be a Amd FX4100. HA Reply
  • makaira - Thursday, December 08, 2011 - link

    Well I very excitedly bought a 8150 based system for number crunching as the performance/$ looked very good. I could buy a "quiet" system for Aus $ 1130 with SSD and only 8Gb RAM.
    I had previously purchased a Intel i7 2600K, but could never get it to overclock and run 64 bit Java app (Napoleon Spike from DUG) 24/7, it fell over after 6 hrs or 12 or 23 or 47, it always fell over despite water cooling.
    Now the bulk of my work is done by Xeons in the rack, with a couple of dual 5680's systems doing the heavy lifting (2 x 6 core + hyperthreading looks like 24 CPU's to OS). These are good stable systems with 96Gb RAM, but high overall system cost.
    I wanted a few cheap and moveable fast CPU's. Boy did the Bulldozer fail to deliver
    More is Better measure in Bytes inversion throughput/minute
    BD 8150 115-123k in 8/8 threads i.e. flat out
    i7 2600 237-268k in 8/8 threads i.e. flat out
    Xeon dual 5680 333-356k in 12/24 threads i.e.half loaded
    i7-870 166k in 8/8 threads i.e flat out
    Xeon Dual E5520 190k 12/16 threads
    Xeon Dual 5430 132k 8/8 threads

    The Bulldozer is the slowest and the newest....very poor performance. Eclipsed by Intel at similiar price point. I might as well replace the MB and CPU and go with i73960 or 3930...
    Reply
  • wepexpert117 - Thursday, December 08, 2011 - link

    I dunno if anyone noticed, but if u study the architectures carefully, then what AMD calls as a 'module' is comparable to a 'core' of Intels. Intels Hyperthreading allows two logical thread executions per core. But AMD's TruCore theory, only allows one thread per core. The Intel i5-2500K has 4 physical cores and 8 logical threads. Compared to that the most powerful of the AMD, the FX-8170, contains 4 modules which can execute 8 threads, with 2 cores per module, each core executing 1 thread. On the other hand the i7-2600K contains 6 physical cores and 12 logical threads. Hence by no chance, can the FX-8150, can match the capability of the 2600K, as the latter as 2 more cores to add to the power. As for the results of the benchmarking, it also agrees with the fact that the FX-8150 is comparable albeit a little less powerful than the i5-2500K, because of the architecture difference between Intels core and AMD's Bulldozer.If AMD ever brings out (according to them) a 12 core FX processor (Prob. FX-12XXX), then it would be really interesting to see how that matches with the i7-2600K. Altough the shared L2 cache architecture, is what may be detrimental to the performance of these processors. Reply
  • Jondenmark - Saturday, December 24, 2011 - link

    Something is wrong. If I look at a die shot of Llano then the core is about 1½ times the size of the 1 MB L2 cache. If I look at a Bulldozer module, it is about 1½ times the 2 MB L2 cache. To me this indicates, that a Buldozer module is about 100% larger than a phenom II core which is far from the 12% more core size, which AMD has previously indicated was the cost of adding another core to form a module. The 12% was expected to allow AMD to add nearly double the core count on a given process node to convince the server market and give plenty of die space for the GPU on the Llano APU. Where am I wrong and what is right? Reply
  • 8 core cpu - Friday, January 06, 2012 - link

    This <a herf="http://8corecpu.com/">8 Core Cpu</a> is high spreed CPU. It is best than other CPU Reply
  • 8 core cpu - Friday, January 06, 2012 - link

    This 8 Core Cpu is high spreed CPU. It is best than other CPU. For more info please ....
    http://8corecpu.com/
    Reply
  • Raven0628 - Saturday, January 14, 2012 - link

    I beleive amd realy missed it shoot badly, but it is still the right social choice caus what will happen if intel get x86 monopol and they are still resonably priced and whene you have to live with it in every day life will you realy notice the diferance in perfomance. Unless you realy to go for all the top of the line in every part of your system you will got for the top of intel i7.
    But i'v never did and alway ended up with reliable good perfomance amd sys for less than 800$ counting with the power supply i had to replace. this year. my point unless you want a death machine go for amd and you will feel better with your self ;).
    PS. sry for the terible english.
    Reply
  • Ernst0 - Sunday, February 05, 2012 - link

    Hey guys.

    There is no doubt that whatever critiques have been posted are valid but I skimmed a few pages and saw no "Consumer" comments.

    I have purchased an 8150 with a AMD3+ motherboard and will be putting the unit together.

    In my days since the Z80 and 48k this represents the nicest cpu ever for me.
    That it was affordable and that I will have 8 cores to task with my hobby programming such as trying to factor RSA-numbers or the ilk the AMD 8=core is a dream system for the price.

    I picked up case, mother board power supply, 1.5 TB drive DVD, 1 gb video, 16 gb ram, 28 inch monitor, wall mount for monitor so I can have two 28's with one the long way for source code and perhaps something else.. Anyway $1200 is the cost.
    Now this is my first bare-bones experience too so all in all it is exciting to get such a dream machine and I am happy to step forward and support AMD

    I don't know what awaits when the memory arrives and I boot up but it feels like Starship already and I have vowed to learn OpenMP under GCC to advance into multi-core programming.

    So perhaps there will be issues. perhaps this is not all that nor is it wat will come but from where I am at I am still on the AMD home team and my money is flowing in the economy.

    I went from trs 80 to Amiga then to twin AMD single core chips on one Motherboard, Moved to the early quad cores dreaming of dual quad cores when a system with 8 cores of that day would have cost $4900 and now picked up a system that as a boy in 1973 I would have considered Alien-ufo technology for about what I paid for dual single core chips just a few years ago.

    So BullDozer can't be all that bad. The price is good! I will see how she runs. I often peg cores at 100% for days when searching for RSA factors.. Looks like I get more bang for the same bucks this time and I am all for that.

    Thank you AMD for such a wonderful cpu. I plan to make use and thanks to the motherboard I can watch out for heat issues much easier than ever,

    Not to mention it looks like the sound system is way advanced over the last computer as well.

    So from a consumer / hobby programmer point of view this is very cool indeed.

    Ernst
    Reply
  • mumbles - Sunday, February 12, 2012 - link

    Thank you for being the first to actually contribute some real world response to this architecture. So many trolls on this thread that are intel fanboys.

    Also, if your using xen with this thing, I would be interested in seeing some feedback on how multiple guests(like more than 4) act when trying to fight for floating point processor time. Be interesting also to see if 4 floating point threads and 4 integer threads can all run at the same time with no waiting. That might be asking too much for now tho.
    Reply

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