Re: [Xen-devel] A good way to speed up the xl destroy time(guest page scrubbing)

[Bob Liu <bob.liu@xxxxxxxxxx>]

On 12/05/2014 08:24 PM, Jan Beulich wrote:
>>>> On 05.12.14 at 11:00, <bob.liu@xxxxxxxxxx> wrote:
>> 5. Potential workaround
>> 5.1 Use per-cpu list in idle_loop()
>> Delist a batch of pages from heap_list to a per-cpu list, then scrub the
>> per-cpu list and free back to heap_list.
>>
>> But Jan disagree with this solution:
>> "You should really drop the idea of removing pages temporarily.
>> All you need to do is make sure a page being allocated and getting
>> simultaneously scrubbed by another CPU won't get passed to the
>> caller until the scrubbing finished."
> 
> So you don't mention any downsides to this approach. If there are
> any, please name them. If there aren't, what's the reason not to
> go this route?

The reason was what you suggested was not very specific, I still have no
idea how to implement a patch which can "make sure a page being
allocated and getting simultaneously scrubbed by another CPU won't get
passed to the caller until the scrubbing finished".

Thanks,
-Bob

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