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Date:      Sun, 13 Sep 2015 14:52:08 +0300
From:      Dmitry Sivachenko <trtrmitya@gmail.com>
To:        FreeBSD Stable ML <stable@freebsd.org>
Subject:   process scheduling and cpuset
Message-ID:  <623FA99E-04E7-4D29-953A-61EE7B35CBF6@gmail.com>

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Hello,

I have 32 processor machine (2x CPU E5-2650) running several CPU-bound =
processes (ULE scheduler).
3 processes are 32-threaded, and 8 are single threaded.

I bind all 3 32-threaded processes to CPUs 0-24 (cpuset -C -l 0-24 -p =
XXX).

I expect that the remaining 8 single-threaded processes will (mostly) =
run on the remaining 25-31 CPU cores and use (almost) 100% cpu each.

But this is not the case (according to top(1)):  they spend a lot of =
time on 0-24 CPUs and CPU Idle time is about 10%.

These are all purely computational programs, in idle system =
single-threaded programs steadily consume 100% of a core, and =
32-threaded programs consume all 32 cores and idle time is zero.

Is it an ULE scheduler feature or am I doing something wrong?

The goal is to give a single-threaded program a chance to run when =
somebody started several 32-threaded processes.

Thanks!=



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