ULE vs. 4BSD in RELENG_7

Josh Carroll josh.carroll at gmail.com
Tue Oct 23 09:28:52 PDT 2007


I posted this to the stable mailing list, as I thought it was
pertinent there, but I think it will get better attention here. So I
apologize in advance for cross-posting if this is a faux pas. :)

Anyway, in summary, ULE is about 5-6 % slower than 4BSD for two
workloads that I am sensitive to: building world with -j X, and ffmpeg
-threads X. Other benchmarks seem to indicate relatively equal
performance between the two. MySQL, on the other hand, is
significantly faster in ULE.

I'm trying to understand why ffmpeg and buildworld are slower in ULE
than 4BSD, since it seems to me that ULE was supposed to be the better
scaling scheduler.

Here is a link to the original thread on the stable mailing list:


Remy replied with some interesting results for building world between
the two schedulers on an 8-way system. It seems that ULE suffers as
more threads/processes are thrown at it, at least it appears that way
from Remy's data.

Does anyone have any additional performance tests I can run that might
help indicate where the deficiency is in the ULE scheduler? MySQL
performance is excellent, so I'm wondering if it was tuned to that
particular workload?

I'm not sure if Remy subscribes to this list, so I am CC'ing him. Hope
you don't mind Remy :)


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