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Re: [PATCH 0/2] xen/mm: limit in-place scrubbing
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- Date: Fri, 9 Jan 2026 11:34:03 +0000
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <bertrand.marquis@xxxxxxx>, Michal Orzel <michal.orzel@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Anthony PERARD <anthony.perard@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, Roger Pau Monne <roger.pau@xxxxxxxxxx>
- Delivery-date: Fri, 09 Jan 2026 11:34:17 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 09/01/2026 11:32 am, Jan Beulich wrote:
>>> Or is this when very many CPUs
>>> try to do the same in parallel?
>> The scenario is reboot of a VM when Xapi is doing NUMA placement using
>> per-node claims.
>>
>> In this case, even with sufficient scrubbed RAM on other nodes, you need
>> to take from the node you claimed on which might need scrubbing.
> Much like if there was an exact-node request without involving claims.
>
>> The underlying problem is the need to do a long running operation in a
>> context where you cannot continue, and cannot (reasonably) fail.
> Right.
Yeah - I think this is a scenario that could happen without NUMA
aspects, if the system is almost full. I suspect we've just made it
easier to hit, or we've got better testing. Hard to say.
~Andrew
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