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Date:      Wed, 24 Oct 2007 09:39:29 -0400
From:      "Josh Carroll" <josh.carroll@gmail.com>
To:        "Bruce Evans" <brde@optusnet.com.au>
Cc:        remy.nonnenmacher@activnetworks.com, Kris Kennaway <kris@freebsd.org>, freebsd-performance@freebsd.org
Subject:   Re: ULE vs. 4BSD in RELENG_7
Message-ID:  <8cb6106e0710240639r20e03ce9w81ed3354338b7395@mail.gmail.com>
In-Reply-To: <20071024171915.E84143@delplex.bde.org>
References:  <8cb6106e0710230902x4edf2c8eu2d912d5de1f5d4a2@mail.gmail.com> <471E343C.2040509@FreeBSD.org> <20071024171915.E84143@delplex.bde.org>

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> 5-6% is a lot.  ULE has some tuning for makeworld in -current, which
> for me reduced it to less than 1% slower than 4BSD (down from 5-10%
> slower), for the case of makeworld -j4 over nfs on a 2-CPU system with
> the sources pre-cached on the server and objects on a local file system,
> and extensive local tuning of makeworld, nfs and network drivers.  I
> think the tuning in ULE was mainly for a 2-CPU system, because makeworld
> seemed to be very bad under ULE only with 2 CPUs.  Apparently, it is also
> very bad with more CPUs.  There are sysctls to modify the ULE tuning.

I found Kris' document here:

http://people.freebsd.org/~kris/scaling/mysql.html

Which also mentions some ULE tuning. The sched_ule man page doesn't
mention what these are. Can someone point me to a document that
explains the sysctl tuning I can try?

I imagine I would want to tweak one or more of these:

kern.sched.preemption: 1
kern.sched.topology: 0
kern.sched.steal_thresh: 2
kern.sched.steal_idle: 1
kern.sched.steal_htt: 1
kern.sched.balance_interval: 133
kern.sched.balance: 1
kern.sched.tryself: 1
kern.sched.affinity: 3
kern.sched.pick_pri: 1
kern.sched.preempt_thresh: 64
kern.sched.interact: 30
kern.sched.slice: 13

But I'm not sure which to try. I did try setting kern.sched.pick_pri
to 0, but that hasn't helped the ffmpeg workload at least.

Thanks,
Josh



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