Apparent performance regression 8.3@ -> 8.4 at r255966?

[Ivan Voras]

On 07/10/2013 19:28, David Wolfskill wrote:> At work, we have a bunch of
machines that developers use to build some
> software.  The machines presently run FreeBSD/amd64 8.3-STABLE @rxxxxxx
> (with a few local patches, which have since been committed to stable/8),
> and the software is built within a 32-bit jail.
> 
> The hardware includes 2 packages of 6 physical cores each @3.47GHz
> (Intel X5690); SMT is enabled (so the scheduler sees hw.ncpu ==
> 24).  The memory on the machines was recently increased from 6GB
> to 96GB.
> 
> I am trying to set up a replacement host environment on my test machine;
> the current environment there is FreeBSD/amd64 8.4-STABLE @r255966; this
> environment achieves a couple of objectives:
> 
> * It has no local patches.
> * The known problems (e.g., with mfiutil failing to report battery
>   status accurately) are believed to be addressed appropriately.
> 
> However: when I do comparison software builds, the new environment is
> taking about 12% longer to perform the same work (comparing against a
> fair sample of the deployed machines):

So, the test machine is exactly the same as the old machines? Does the
hardware upgrade coincide with 8.4-STABLE upgrade?

At a guess, you also might be hitting a problem with either NUMA (which
would mean the difference you encountered is pretty much random,
depending on how the memory from your processes was allocated), or a
generic scheduler issue (IIRC, FreeBSD 9 series was found to be much
more scalable for > 16 CPUs).

Just a thought - you *could* set up an 8-STABLE jail in a 9-STABLE
environment if you need the 8-STABLE libraries for your software.



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