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Re: 7.0 CPU and Memory Performance



Tim Traver wrote:

Robert Watson wrote:
On Tue, 12 Aug 2008, Tim Traver wrote:

I have recently had the opportunity to upgrade a few servers from old
versions of 5.4 to 7.0, and have seen some interesting data. Before
doing this, I wanted to take some benchmarks to see how the scripts
that I would run would fare between the two versions, and the results
are somewhat confusing...
There are potentially a lot of variables here, you migh want to try
fiddling with the following and see what difference it makes:

(1) Try both 4BSD and ULE in 7.0 -- they have different properties,
and at the
    very least it would be nice to see what impact it has.

(2) Statically compile the 5.4 binary, and run the same binary on both
5.4 and
    7.0 -- there have been lots of compiler changes, which might be
relevant.

Also, can you confirm that you're running either 32-bit or 64-bit
kernels consistently on both versions of FreeBSD?

Robert N M Watson
Computer Laboratory
University of Cambridge


Robert,

ok, I looked and it looks like the port compiles statically, and I was
able to grab the binary from the old disk and move it over to the new one...

here is info now on how it is linked :

[root ~]# ldd ubench.5.4
ubench.5.4:
        libm.so.3 => /usr/local/lib/compat/libm.so.3 (0x2807e000)
        libc.so.5 => /usr/local/lib/compat/libc.so.5 (0x28099000)
[root ~]# ldd /usr/local/bin/ubench
/usr/local/bin/ubench:
        libm.so.5 => /lib/libm.so.5 (0x2807f000)
        libc.so.7 => /lib/libc.so.7 (0x28094000)

where ubench is the locally compiled one...

For reference, here are the old stats
FreeBSD 5.4 - CPU 112,721 - MEM - 146,483
FreeBSD 7.0 - CPU 177,339 - MEM - 95,920

And here is the run of the ubench.5.4 binary:
FreeBSD 7.0 - CPU 139,623 - MEM - 207,180

And a rerun of the FreeBSD 7.0 ubench making sure there is absolutely no activity on the box
FreeBSD 7.0 - CPU 200,562 - MEM - 107,695

That run is a little better than the previous one, but there seems to still be quite a difference in the memory tests...

Does that show anything ????

It shows that if there is a difference it is probably in userland, not the kernel. The obvious guess is the new malloc in 7.0. As for whether it indicates a bug, someone would have to look more closely at what ubench does. The author's description of his benchmark doesn't inspire confidence: it does "rather senseless memory allocation and memory to memory copying operations for another 3 mins concurrently using several processes".

Kris
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