Thanks Kris,
Moving to freebsd-performance.
Hi all,
When running NASA's NAS Parallel Benchmarks [1] under Phoronix Test
Suite [2] on PC-BSD 8.1, we are seeing a scalability issue on Intel's
new Sandybridge hardware.
We see scalability at 1, 2 and 6 processors enabled (via BIOS). At 3 &
4 cores, we're seeing drop off in some tests, or a collapse in
performance in others. Although it may be a quirk on the Sandybridge
hardware, it may also be a scalability issue in general.
Attached are two images showing the collapse in scalability. The LU.A
test was unable to complete in a reasonable time (hours, vs the expected
minutes) and was aborted. Interestingly the scalability at 6 cores were
in line with the other platforms.
To repeat these tests, you can download Phoronix Test Suite 3 RC and run
the NAS Parallel Benchmarks via the command
./phoronix-test-suite benchmark pts/npb
And choose either the MG.B or LU.A subtest. We'll be trying to remove
the HW from being a potential factor.
Also note that scalability of 6 cores + HyperThreading also dropped off
fairly heavily (so did OpenIndiana).
Thanks in advance.
Matthew
[1] http://www.nas.nasa.gov/Resources/Software/npb.html
[2] http://www.phoronix-test-suite.com/
On 02/14/2011 06:16 AM, Kris Moore wrote:
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On 02/14/2011 02:09, Matthew Tippett wrote:
Hi Kris,
I work with Michael Larabel, of Phoronix fame. We've recently run some
benchmarks with a core i7 970 against OpenIndiana, PC-BSD and Ubuntu
with various cores turned off.
One interesting behaviour that we saw is that between 3 and 4 cores
running the performance of PC-BSD dropped fairly badly in some of the
NAS parallel benchmarks. The system performs reasonably well for 1,2
and 6 cores. Is this performance behaviour known within the PC-BSD
community? It is fairly easy to reproduce the results with the Phoronix
Test Suite and we'd be happy to work with some developers in determining
the underlying issue.
Note, however that the article covering this benchmark will probably get
published over the next few days.
Regards,
Matthew
Matthew,
Thanks for the heads up! What specific types of benchmarks are falling
behind? On the PC-BSD side we mostly handle usability stuff, and don't
monkey with the FreeBSD internals, so this may best be a question for
the FreeBSD Performance mailing list. I'm sure you'll get all kinds of
comments there on how to improve the scalability tuning, and if there is
still an issue then those will be the people who can fix it :)
http://lists.freebsd.org/mailman/listinfo/freebsd-performance
- --
Kris Moore
PC-BSD Software
iXsystems
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