performance degradation in 6.2 when adding a second quad core
bthielsen at safarivideonetworks.com
Fri Feb 22 14:35:52 UTC 2008
On Feb 21, 2008, at 17.49, Kris Kennaway wrote:
> benjamin thielsen wrote:
>> hi folks-
>> we've been experiencing some interesting behavior on single quad
>> core computers as compared to dual quad core computers.
> Yes, this can happen when you run into concurrency bottlenecks in
> the application or in the kernel.
>> it appears that adding a second processor to the system (leaving it
>> otherwise untouched) actually decreases performance. we've got a
>> small rudimentary test process, built in house, that does
>> postgresql queries (selects) via http requests (apache2/php5).
> 7.0 will perform much better than 6.x on SMP workloads in general,
> however TCP I/O is not yet at the point where it can make efficient
> use of many processors (there has been a lot of work on TCP in 7.0,
> but it is not yet at the stage where a performance payoff will be
> seen with more than about 4 CPUs). This is one of the projects that
> we will be working on this year, so you can expect future releases
> to have improved concurrent TCP performance.
> There may be other issues, so if you like you can enable
> LOCK_PROFILING and obtain a trace when your workload is running (see
> the manpage). You should also try the ULE scheduler on 7.0.
i apologize - i neglected to mention that we are using ule on 7.0.
what do you guys generally endorse/recommend for local(non-network)
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