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[Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucur


From: Avi Kivity
Subject: [Qemu-devel] Re: [kvm-devel] [PATCH 0/4] Rework alarm timer infrastrucure - take2
Date: Sun, 19 Aug 2007 11:24:18 +0300
User-agent: Thunderbird 2.0.0.0 (X11/20070419)

Anthony Liguori wrote:
I think this is a really nice and important patch set.  Just a couple
things:

On Sun, 2007-08-19 at 00:02 +0200, Luca Tettamanti wrote:

In this case the dyn-tick minimum res will be 1msec. I believe it should
work ok since this is the case without any dyn-tick.
Actually minimum resolution depends on host HZ setting, but - yes -
essentially you have the same behaviour of the "unix" timer, plus the
overhead of reprogramming the timer.

Is this significant?  At a high guest HZ, this is could be quite a lot
of additional syscalls right?


At HZ=1000, this adds a small multiple of 1000 syscalls, which is a fairly small overhead. At HZ>1000 (only possible with a dyntick guest), the current implementation doesn't cope at all, so we can't compare overhead.

--
error compiling committee.c: too many arguments to function





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