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Re: [Xen-devel] linux: {start, stop}_hz_timer() not really affecting per

To: Jan Beulich <jbeulich@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] linux: {start, stop}_hz_timer() not really affecting periodic timer?
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Wed, 16 Jan 2008 14:37:51 +0000
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Thread-topic: [Xen-devel] linux: {start, stop}_hz_timer() not really affecting periodic timer?
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No, no, and no. :-)

start/stop_hz_timer() refer to Linux's own hz ticker. Xen does not deliver
periodic ticks when a guest is descheduled, so the Xen side of things is
implicitly handled already. There is no need for start/stop_hz_timer to
execute hypercalls to enact this.

The call to VCPUOP_set_singleshot_timer cannot return -ETIME because the
kernel does not specify the VCPU_SSHOTTMR_future flag.

All this assume you are looking at linux-2.6.18-xen.hg.

 -- Keir

On 16/1/08 14:32, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

> Shouldn't these two functions call VCPUOP_set_periodic_timer/
> VCPUOP_stop_periodic_timer to actually do what their names promise?
> 
> And shouldn't the call to VCPUOP_set_singleshot_timer permit -ETIME
> without BUG()?
> 
> Jan
> 
> 
> _______________________________________________
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> http://lists.xensource.com/xen-devel



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