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From: Zachary Amsden <zach@vmware.com>
To: Keir Fraser <keir@xensource.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
	xen-devel@lists.xensource.com, virtualization@lists.osdl.org,
	Steven Hand <steven.hand@cl.cam.ac.uk>,
	linux-kernel@vger.kernel.org, Chris Wright <chrisw@sous-sol.org>,
	Andi Kleen <ak@muc.de>, Andrew Morton <akpm@linux-foundation.org>,
	Ian Pratt <Ian.Pratt@xensource.com>,
	Christian Limpach <Christian.Limpach@xensource.com>
Subject: Re: [Xen-devel] Re: [patch 14/21] Xen-paravirt: Add XEN config	options and disableunsupported config options.
Date: Fri, 16 Feb 2007 13:51:21 -0800	[thread overview]
Message-ID: <45D62759.7080006@vmware.com> (raw)
In-Reply-To: <C1FBAFD7.99AB%keir@xensource.com>

Keir Fraser wrote:
> On 16/2/07 17:46, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote:
>
>   
>> Keir Fraser wrote:
>>     
>>> This initial patchset does not include save/restore support anyway, so in
>>> fact it would be consistent to have CONFIG_PREEMPT configurable. I'm sure
>>> that we are going to have some nasty bugs to fix up as a result, but we
>>> can't fix them until we find them! Then we can convert our save/restore code
>>> to use the freezer before submitting it for inclusion.
>>>       
>> OK.  So that makes the only config restriction the 100Hz ticks.
>>     
>
> We can extend the Xen timer interface quite easily and get rid of this one
> too. In fact it doesn't *much* matter if the CONFIG_HZ differs from the Xen
> ticker rate -- we modified the Linux timer ISR to handle timer interrupts at
> arbitrary times already. The only drawback is that jiffies updates in burts
> if CONFIG_HZ is higher than the actual tick rate, and this can affect some
> calibration constants and cause Linux to print out some weird values at
> start-of-day.
>   

That's why we'd very much like to get a get_cpu_speed paravirt-op 
implemented.  I think this would be useful to work around these problems 
for Xen as well.

Zach

  parent reply	other threads:[~2007-02-16 21:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-16 10:00 Christian Limpach
2007-02-16 10:09 ` Andrew Morton
2007-02-16 10:47   ` Keir Fraser
2007-02-16 10:54     ` Andrew Morton
2007-02-16 11:03       ` Keir Fraser
2007-02-16 17:46         ` [Xen-devel] " Jeremy Fitzhardinge
2007-02-16 19:00           ` Keir Fraser
2007-02-16 19:24             ` Jeremy Fitzhardinge
2007-02-16 21:51             ` Zachary Amsden [this message]
2007-02-16 22:38               ` Dan Hecht
2007-02-17 15:06                 ` Rik van Riel

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