Re: [Xen-devel] [PATCH v3 7/9] mm: Keep pages available for allocation while scrubbing

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 05/04/2017 12:03 PM, Jan Beulich wrote:
>>>> On 14.04.17 at 17:37, <boris.ostrovsky@xxxxxxxxxx> wrote:
>> Instead of scrubbing pages while holding heap lock we can mark
>> buddy's head as being scrubbed and drop the lock temporarily.
>> If someone (most likely alloc_heap_pages()) tries to access
>> this chunk it will signal the scrubber to abort scrub by setting
>> head's PAGE_SCRUB_ABORT bit. The scrubber checks this bit after
>> processing each page and stops its work as soon as it sees it.
> Explanation sounds fine, but didn't you earlier indicate you think
> yourself that the title is not really suitable (anymore)? I'm of
> that opinion, at least, as pages are always available now, it's just
> that the latency to get hold of the heap lock is higher before this
> change than what we want it to be.

Uhm... Yes, that's what it meant to say ;-)

Should have been "Keep *heap* available to others while scrubbing"

-boris

>
> Looking at the patch itself is not overly useful as it seems without
> the disposition of patch 5 being clear.
>
> Jan
>


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