ULE vs. 4BSD in RELENG_7
kris at FreeBSD.org
Tue Oct 23 10:49:48 PDT 2007
Josh Carroll wrote:
> 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 :)
One major difference is that your workload is 100% user. Also you were
reporting ULE had more idle time, which looks like a bug since I would
expect it be basically 0% idle on such a workload.
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