Date: Fri, 4 Dec 2009 22:09:59 +0100 From: Ivan Voras <ivoras@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: freebsd-hackers@freebsd.org Subject: Re: Request for information - timers, hz, interrupts Message-ID: <9bbcef730912041309m51ce4858q42937e0f76f94cda@mail.gmail.com> In-Reply-To: <200912041047.08253.jhb@freebsd.org> References: <hfb7ne$mi$1@ger.gmane.org> <200912041047.08253.jhb@freebsd.org>
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2009/12/4 John Baldwin <jhb@freebsd.org>:
> On Friday 04 December 2009 9:52:39 am Ivan Voras wrote:
>> For a long time, at least in the 6-stable timeframe, I was used to
>> seeing timer interrupts going at the frequency of 2*HZ, e.g. this is
>> from 6.4-RELEASE:
>>
>> kern.clockrate: { hz =3D 250, tick =3D 4000, profhz =3D 1000, stathz =3D=
142 }
>> kern.hz: 250
> It actually was changed to provide saner behavior when you use low hz val=
ues
> like 'hz=3D100'. =C2=A0Note that your stathz is now 142 instead of 33. =
=C2=A0The scheduler
> is likely far happier with that stathz. =C2=A0There is more detail in the=
commit
> log I believe (just look at the logs for local_apic.c in either svn or
> cvsweb).
Ok. Some more questions:
What does "ticks" do in the above sysctl output?
So 4000 interrupts/s per CPU in the default configuration isn't
considered excessive? :)
I see stathz isn't a divisor of any number in kern.clockrate, which
probably means it's not triggered from one of them firing; can't it be
a separately configurable value?
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