memtest86 results on various computers

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memtest86 results on various computers

Postby TerraFrost » Sat Mar 13, 2010 7:01 am

(sorted by L1 cache speed)
  1. Intel Core i5 1729 MHz
    L1 Cache: 32K 69162 MB/s
    L2 Cache: 256K 26197 MB/s
    L3 Cache: 8192K 19648 MB/s
    Memory: 3132 10607 MB/s
  2. Pentium D (65nm) 3200 MHz
    L1 Cache: 16K 20916 MB/s
    L2 Cache: 512K 16932 MB/s
    L3 Cache: None
    Memory: 1471M 844 MB/s
  3. Pentium M (0.09) 1599 MHz
    L1 Cache: 32K 18375 MB/s
    L2 Cache: 2048K 8458 MB/s
    L3 Cache: None
    Memory: 1527M 952 MB/s
  4. Pentium M (0.13) 1595 MHz
    L1 Cache: 32K 17335 MB/s
    L2 Cache: 1024K 8667 MB/s
    L3 Cache: None
    Memory: 767M 603 MB/s
  5. Pentium 4 (0.13) 1794 MHz
    L1 Cache: 8K 13001 MB/s
    L2 Cache: 512K 11356 MB/s
    L3 Cache: None
    Memory: 757M 876 MB/s
  6. Pentium 4 (0.18) 1396 MHz
    L1 Cache: 8K 10494 MB/s
    L2 Cache: 256K 9122 MB/s
    L3 Cache: None
    Memory: 639M 1082 MB/s
  7. Pentium 4 (0.13) 1196 MHz
    L1 Cache: 8K 8667 MB/s
    L2 Cache: 512K 7338 MB/s
    L3 Cache: None
    Memory: 255M 885 MB/s
  8. Pentium III 824.7 MHz
    L1 Cache: 16K 7707 MB/s
    L2 Cache: 256K 3221 MB/s
    L3 Cache: None
    Memory: 383M 220 MB/s
The first computer is actually a brand new Core i7. A quad-core one, at that. It has 8GB in it, as well - not 3GB. The RAM: 4x 2GB PC3-8500 SODIMMs. What's interesting about that one is the speed: 10607 MB/s. That's faster than the last three computers L1 caches.

Also, the first computer's RAM is faster by leaps and bounds than the rest. The next fastest RAM is in the computer with the third slowest L1 cache. A computer from 2001 using 2x 256MB PC-800 RIMMs and 2x 128MB PC-800 RIMMs. Not even the computer with the second fastest L1 cache comes close and that computer's from 2006. Uses PC-2700 DIMMs, as I recall.

Finally, of all these computers, the first computer is the only one with an L3 cache. Kinda make me wonder L3 caches have been around.
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Re: memtest86 results on various computers

Postby Nuxius » Tue Mar 16, 2010 6:05 am

TerraFrost wrote:Finally, of all these computers, the first computer is the only one with an L3 cache. Kinda make me wonder L3 caches have been around.

Because before the Core i3/5/7 series, the memory controller was located on the motherboard, and so L3 cache was there too, and motherboard makers didn't like the added cost.
However, ever since Intel integrated the memory controller on die with the Core i3/5/7, L3 cache can be put there as well, so motherboard makers need not worry about it anymore. So now the amount/presence of L3 cache, like L2 and L1 cache, can be decided by Intel themselves.
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Re: memtest86 results on various computers

Postby TerraFrost » Wed Mar 17, 2010 9:23 pm

Nuxius wrote:
TerraFrost wrote:Finally, of all these computers, the first computer is the only one with an L3 cache. Kinda make me wonder L3 caches have been around.

Because before the Core i3/5/7 series, the memory controller was located on the motherboard, and so L3 cache was there too, and motherboard makers didn't like the added cost.
However, ever since Intel integrated the memory controller on die with the Core i3/5/7, L3 cache can be put there as well, so motherboard makers need not worry about it anymore. So now the amount/presence of L3 cache, like L2 and L1 cache, can be decided by Intel themselves.

That kinda makes me think of Pentium II's and how they used to come in cartridges:

http://en.wikipedia.org/wiki/File:Intel ... _SECC2.jpg

To quote from the wikipedia.org article on Pentium II's:

Unlike previous Pentium and Pentium Pro processors, the Pentium II CPU was packaged in a slot-based module rather than a CPU socket. The processor and associated components were carried on a daughterboard similar to a typical expansion board within a plastic cartridge. A fixed or removable heatsink was carried on one side, sometimes using its own fan.[2]

This larger package was a compromise allowing Intel to separate the secondary cache from the processor while still keeping it on a closely coupled back-side bus.

One thing I'm a little unclear about, still... according to wikipedia.org, there are 4 x 256 KB L2 caches. If the operating system was only using one care and Turbo Boost was being used to speed up that one core (which would presumably mean all four cores were working as one), would all four L2 (and L1, for that matter) caches be in use or would just one cache be in use? And if they were in use, I assume all the cores would have the same data?
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Re: memtest86 results on various computers

Postby Nuxius » Tue Mar 30, 2010 9:58 am

TerraFrost wrote:(which would presumably mean all four cores were working as one)

This is incorrect, each core is still independent. If all of the cores are not in use, and a demanding application is pushing the cores it is using to their limits, then Turbo Boost kicks in to overclock the cores that are in use. Since all of the cores are not in use, you have the headroom to run them a bit faster. (man I sure did use variations of "cores in use" a lot there :p)
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Re: memtest86 results on various computers

Postby TerraFrost » Wed May 05, 2010 11:00 pm

http://slashdot.org/comments.pl?sid=164 ... d=32092668

That reminded me of this post. Per that, on desktop CPU's, overclocking isn't really necessary since the cores are likely running pretty close to their max clock speed, anyway, but on laptop CPU's, where you don't have as much room for cooling, multiple cores running means more heat and that performance has to be throttled accordingly. So maybe thinking of it as Turbo Boost isn't appropriate but rather as Turbo Slowdown, heh. ie. it's not that the CPU speeds up when fewer cores are in use - it's that it slows down when more cores are in use.
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