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Re: [Xen-devel] [PATCH 4/6] xen: don't free percpu areas during suspend


  • To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx
  • From: Juergen Gross <jgross@xxxxxxxx>
  • Date: Wed, 27 Mar 2019 17:18:27 +0100
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  • Cc: Wei Liu <wei.liu2@xxxxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Wed, 27 Mar 2019 16:18:36 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
  • Openpgp: preference=signencrypt

On 27/03/2019 16:55, Andrew Cooper wrote:
> On 18/03/2019 13:11, Juergen Gross wrote:
>> Instead of freeing percpu areas during suspend and allocating them
>> again when resuming keep them. Only free an area in case a cpu didn't
>> come up again when resuming.
>>
>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> 
> Hmm - this is slightly problematic, given the dual nature of this code.
> 
> I agree that it this change is beneficial for the suspend case, but it
> is a problem when we are parking an individual CPU for smt=0 or
> xen-hptool reasons.
> 
> Do we have any hint we can use when taking the CPU down as to whether
> we're expecting it to come straight back up again?

Did you look into the patch? I did this by testing system_state.


Juergen

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