From: Andi Kleen <andi@firstfloor.org>
To: Alexander Graf <agraf@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>,
"David S. Ahern" <daahern@cisco.com>,
kvm-devel <kvm@vger.kernel.org>,
Marcelo Tosatti <mtosatti@redhat.com>,
Glauber de Oliveira Costa <gcosta@redhat.com>,
Avi Kivity <avi@redhat.com>
Subject: Re: gettimeofday "slow" in RHEL4 guests
Date: Tue, 25 Nov 2008 12:48:15 +0100 [thread overview]
Message-ID: <20081125114815.GG6703@one.firstfloor.org> (raw)
In-Reply-To: <426B9829-823B-40BE-9A7E-9F7EF2ED3412@suse.de>
> Why does hpet need to be slow? Can't you just 1:1 pass through one of
> the hpet timers if you only have a limited amount of vms?
HPET is not a truly virtualizable device, it's all the counters
in one block that cannot be really mapped to different people.
Also most systems have very little counters and Linux typically needs two
at least (system timer and /dev/hpet)
> If done cleverly this might even work if #hpet > #cpu.
Sure with a device model, but that needs vmexits.
-Andi
next prev parent reply other threads:[~2008-11-25 11:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-24 17:47 gettimeofday "slow" in RHEL4 guests David S. Ahern
2008-11-25 4:41 ` David S. Ahern
2008-11-25 10:14 ` Andi Kleen
2008-11-25 11:17 ` Alexander Graf
2008-11-25 11:48 ` Andi Kleen [this message]
2008-11-25 12:13 ` Alexander Graf
2008-11-25 12:52 ` Andi Kleen
2008-12-28 18:38 ` Marcelo Tosatti
2008-12-29 12:37 ` Yang, Sheng
2008-12-29 13:11 ` Avi Kivity
2008-12-29 16:12 ` Dor Laor
2008-12-29 16:27 ` Avi Kivity
2008-12-29 16:29 ` Avi Kivity
2008-11-25 17:20 ` Hollis Blanchard
2008-11-25 19:09 ` David S. Ahern
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