Date: Fri, 30 Jan 2009 11:14:19 +0100 From: Ivan Voras <ivoras@freebsd.org> To: Julian Stecklina <js@alien8.de> Cc: freebsd-xen@freebsd.org Subject: Re: kern.hz = 10 Message-ID: <9bbcef730901300214s19c91071vf9241cd7cd40ba57@mail.gmail.com> In-Reply-To: <871vul1nqk.fsf@tabernacle.localnet> References: <87ocxp1tym.fsf@tabernacle.localnet> <1233285247.24925.4.camel@phoenix.blechhirn.net> <871vul1nqk.fsf@tabernacle.localnet>
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2009/1/30 Julian Stecklina <js@alien8.de>: > Mister Olli <mister.olli@googlemail.com> writes: > >> Hi, >> >> I've never experimented with the kern.hz variable, but on all >> configuration examples for 8-CURRENT if always seen 'kern.hz=100'. >> >>>From where did you get your configuration? > > I use the default config (albeit renamed to BLITZXEN) from 8-CURRENT. Due to bad performance of high HZ in VMs, in 8-CURRENT it is explicitly reduced to 10 if the kernel is running under any kind of virtual environment. This is a somewhat theoretical number and probably needs tuning. If you're interested in trying it out, you can increase it by adding "kern.hz=xxx" to /boot/loader.conf and seeing what is the actual performance influence of high HZ under Xen.
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