From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Jan Beulich <JBeulich@novell.com>
Cc: xen-devel@lists.xensource.com
Subject: Re: [PATCH] x86: extend runstate area updates
Date: Fri, 02 Oct 2009 16:53:13 -0700 [thread overview]
Message-ID: <4AC69269.3050806@goop.org> (raw)
In-Reply-To: <4A8ABF4B020000780001049A@vpn.id2.novell.com>
On 08/18/09 05:48, Jan Beulich wrote:
> In order to give guests a hint at whether their vCPU-s are currently
> scheduled (so they can e.g. adapt their behavior in spin loops), update
> the run state area (if registered) also when de-scheduling a vCPU.
>
> Also fix an oversight in the compat mode implementation of
> VCPUOP_register_runstate_memory_area.
>
> Please also consider for the 3.4 and 3.3 branches.
>
BTW, this actually changes the documented behaviour of
register_runstate_memory_area:
* 2. Only one shared area may be registered per VCPU. The shared area is
* updated by the hypervisor each time the VCPU is scheduled. Thus
* runstate.state will always be RUNSTATE_running and
* runstate.state_entry_time will indicate the system time at which the
* VCPU was last scheduled to run.
not that I think anything was relying on the old behaviour (indeed, it's
pretty unexpected behaviour).
J
next prev parent reply other threads:[~2009-10-02 23:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-08-18 12:48 [PATCH] x86: extend runstate area updates Jan Beulich
2009-08-18 20:28 ` Jeremy Fitzhardinge
2009-10-02 23:53 ` Jeremy Fitzhardinge [this message]
2009-11-20 18:09 ` Ian Campbell
2009-11-20 18:57 ` Ian Campbell
2009-11-21 0:48 ` Jeremy Fitzhardinge
2009-11-21 9:19 ` Ian Campbell
2009-11-24 15:11 ` Ian Campbell
2009-11-23 8:19 ` Jan Beulich
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