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To: FreeBSD Stable <freebsd-stable@FreeBSD.org>
From: Eugene Grosbein <eugen@grosbein.net>
Subject: idprio(1) broken
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Hi!

Is idprio(1) broken in stable/11?

As root, start one bzip2 instance with idprio and one additional bzip2 intance per CPU core:

# idprio 5 bzip2 -9 </dev/zero >/dev/null &
# n=$(sysctl -n kern.smp.cpus)
# i=1; while [ $i -le $n ]; do bzip2 -9 </dev/zero >/dev/null & i=$(($i+1)); done
# top

For dual core system, I see that idprio'd bzip2 takes all cycles of first core
and two "normal" bzip2's share cycles of second core each taking ~50% of CPU time.

It is expected that idprio'd bzip2 get no CPU time at all and each of "normal" bzip2's
get ~100% of single CPU core for such setup.

Eugene Grosbein