Re: [Xen-devel] [PATCH 2 of 4] xenpaging: use wait queues

[Olaf Hering <olaf@xxxxxxxxx>]

On Fri, Dec 02, Andres Lagar-Cavilla wrote:

> > The pager is in the process of writing the gfn to disk after successful
> > nomination. Its next step is the eviction, which will now fail because
> > the p2mt is not p2m_ram_paging_out anymore. It is already prepared for
> > that failure.
> > The previous MEM_EVENT_FLAG_EVICT_FAIL was not needed in the first
> > place.
> Yes it was! The biggest source of overhead is I/O. Tell the pager to stop
> I/O early. Otherwise, you've done the paging out I/O pointlessly, to find
> out only when you try to finalize the eviction.

I'm not sure how to inform the pager, its most likely in the middle of
write(). Since such an event is rare (in my testing at least) I wonder
wether its worth to make it complicated?

Olaf

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