Rik van Riel wrote:

Martin Schwidefsky wrote:

quoted

From: Martin Schwidefsky <redacted>
From: Hubertus Franke <redacted>
From: Himanshu Raj <redacted>

[patch 1/9] Guest page hinting: unused / free pages.

A very simple but already quite effective improvement in the handling
of guest memory vs. host memory is to tell the host when pages are
free. 

Would it be an idea to place this interface in-between the
per-cpu free page lists and the buddy allocator, so we can
move a batch of pages around at once and do the hinting in
a batched fashion ?

That way the overhead will be acceptable not just on S390
(where things are millicoded), but also on hypervisor based
virtualization like Xen.

Easy enough to pass a vector of pages to the hypervisor.

Rik, I thought that what we did.
Martin, I see the code actually does it when the page goes into the hot/cold
list. I can't remember conciously moving to that.
I thought we had a decent hit on the hot/cold, so that bulking makes sense.

Then the interface of bulking could be introduced and for s390 it could internally
be implemented as a sequence of ESSA instruction.
Do you remember the reason why we ended up putting it as part of hot/cold freeing?

-- Hubertus