2 x quad-core system is slower that 2 x dual core on FreeBSD
Kris Kennaway
kris at FreeBSD.org
Mon Nov 19 10:24:14 PST 2007
Alexey Popov wrote:
> Hi.
>
> Robert Watson wrote:
>>> I tried SCHED_ULE, but got no difference:
>> Did you see no change in throughput, or no change in reported CPU use?
> No significant changes.
>
>> We should probably take this thread to performance@ and get Kris
>> involved. He may be interested in trying to reproduce your workload
>> in our testbed so we can perform measurements of our own, as well as
>> getting you to provide profiling information. One of the things we'd
>> most like to have are nice potted benchmarks for real-world workloads,
>> as that allows us to easily replay them, perform measurements,
>> optimize, etc.
> I can provide all profiling or configuration information you ask for.
> Except I can't provide PHP site source codes.
>
> Now I'm in situation that I can't install FreeBSD on all new servers
> because they are all based on 2xquad-core processors and I can't be sure
> it would work good.
Running mutex profiling for e.g. 1 minute of representative load would
be a useful starting point, as well as hwpmc profiling for the same
duration.
My guess is that you're hitting contention in the TCP send path, but I
missed the start of this conversation so I don't know what problems you
are seeing.
Kris
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