Call for testers, amd64 only, new scheduler. (fwd)
jroberson at chesapeake.net
Wed Jun 13 20:38:22 UTC 2007
I'm forwarding this email that I sent to current@ in the hopes that some
performance minded people will tell me their results with this new
---------- Forwarded message ----------
Date: Tue, 12 Jun 2007 19:28:39 -0700 (PDT)
From: Jeff Roberson <jroberson at chesapeake.net>
To: current at freebsd.org
Subject: Call for testers, amd64 only, new scheduler.
This is actually a ULE derivative that I have been discussing for some time.
It is now stable enough that I would like more people to bang on it and give
feedback about performance and tell me about any stability problems they
You can see in the following graph that the ramp-up times for the sysbench
benchmark have improved although the tail has suffered a little:
The new scheduler is FreeBSD-7.0-ULE-pcpulocks. On my dual cpu system the
results are much less ambiguous. It's a 10-15% win on sysbench across the
board. This also improves an artificial thread benchmark included with
sysbench by 500% on an 8 way and gives us ebizzy numbers on par with or better
It also includes a mechanism that should improve bde's nfs buildworld times,
although I have not yet verified that. Hopefully he'll try it as well. It
should reduce CPU idle time while also negating the effects of thrashing other
cpus run queues in the idle thread.
The new patch is at: http://people.freebsd.org/~jeff/schedsmp.diff
You have to change your scheduler to SCHED_SMP. x86 support is forthcoming.
Depending on feedback and what re thinks I am going to consider replacing ULE
entirely with SCHED_SMP or committing this as a seperate scheduler for 7.0.
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