On Tue, Dec 13, 2016 at 03:29:05PM +0100, Laurent Vivier wrote: > > > On 12/12/2016 05:06, David Gibson wrote: > > This introduces stub implementations of the H_RESIZE_HPT_PREPARE and > > H_RESIZE_HPT_COMMIT hypercalls which we hope to add in a PAPR > > extension to allow run time resizing of a guest's hash page table. It > > also adds a new machine property for controlling whether this new > > facility is available, and logic to check that against availability > > with KVM (only supported with KVM PR for now). > > > > Finally, it adds a new string to the hypertas property in the device > > tree, advertising to the guest the availability of the HPT resizing > > hypercalls. This is a tentative suggested value, and would need to be > > standardized by PAPR before being merged. > > Could you explain somewhere what is the aim of the "flags" parameter? > It could help to understand why we have it as it is not used.
It's mostly just there on the general principle that have some way of
extending is a good idea.
As an example of a possible extension, we could have a flag which
caused all the valid HPTEs to be rehashed, instead of just the bolted
ones - we'd need to do tests to see if that was worthwhile (probably a
tradeoff between commit downtime and post-resize performance).
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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