| [eigen] a record for Eigen: 250 GFLOPS !! |
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- To: eigen <eigen@xxxxxxxxxxxxxxxxxxx>
- Subject: [eigen] a record for Eigen: 250 GFLOPS !!
- From: Gael Guennebaud <gael.guennebaud@xxxxxxxxx>
- Date: Wed, 23 Jun 2010 12:04:58 +0200
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Hi,
this morning I played with a 48 cores AMD SMP server (8 processors
AMD-Opteron-8439-SE, 6 cores each @ 2,8 GHz) and a bi-processor made
of Intel X5570 @ 2.93GHz (4 multithreaded cores each => a total of 8
cores, 16 threads), and here are the results for a product of 2048^2
matrices of floats:
** Intel **
16 threads (multi-threading)
eigen real 0.158446s 108.427 GFLOPS (2.22212s)
mt speed up x5.55349 => 34.7093%
8 threads
eigen real 0.125598s 136.785 GFLOPS (1.2581s)
mt speed up x7.0835 => 88.5438%
4 threads
eigen real 0.228977s 75.0287 GFLOPS (2.37034s)
mt speed up x3.88544 => 97.136%
2 threads
eigen real 0.449604s 38.2111 GFLOPS (4.72754s)
mt speed up x1.98317 => 99.1583%
1 thread
eigen mono cpu 0.891639s 19.2677 GFLOPS (8.9178s)
a speed up factor of ~7 for 8 cores is a very nice scaling IMO.
** AMD **
1 thread
eigen mono cpu 1.54084s 11.1496 GFLOPS (15.4136s)
2 threads
eigen real 0.817967s 21.0031 GFLOPS (8.18607s)
mt speed up x1.88375 => 94.1874%
4 threads
eigen real 0.41879s 41.0226 GFLOPS (4.1911s)
mt speed up x3.73174 => 93.2936%
8 threads
eigen real 0.214083s 80.2485 GFLOPS (2.15697s)
mt speed up x7.49282 => 93.6602%
16 threads
eigen real 0.115521s 148.716 GFLOPS (1.26385s)
mt speed up x13.4568 => 84.1048%
24 threads
eigen real 0.168208s 102.135 GFLOPS (1.75357s)
mt speed up x9.55177 => 39.7991%
32 threads
eigen real 0.0686023s 250.427 GFLOPS (1.19708s)
mt speed up x23.001 => 71.8781%
42 threads
eigen real 0.0799503s 214.882 GFLOPS (0.938163s)
mt speed up x19.9015 => 47.3844%
48 threads
eigen real 0.143299s 119.888 GFLOPS (1.62653s)
mt speed up x11.2097 => 23.3536%
We can see that AMD's SSE implementation is half the speed of Intel's
one. This architecture seems to be tricky to control because the peak
performance is obtained with 32 threads with a speed up factor of x23
that is not bad. With more threads the perf significantly drops down.
There is also a slow down with 24 threads.
that's all folks.
gael