Re: [PATCH][4.15] Performance regression due to XSA-336

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Jan Beulich writes ("Re: [PATCH][4.15] Performance regression due to XSA-336"):
> While the change is more intrusive than one would like at this point, an
> up-to-40% regression imo makes this at least a change to be considered
> for 4.15. I will admit though that before next week I won't get around
> to look at this in any more detail than just having read through this
> cover letter. But perhaps someone else might find time earlier.

As I understand it:

This amounts to a request to consider a release ack for "x86/vpt:
Replace per-guest pt_migrate lock with per pt lock".

That patch fixes a regression due to XSA-336.  XSA-336 affected many
versions of Xen.  Therefore this is not a regression between 4.14 and
4.15; rather it's a regresion from pre-XSA-336 to post-XSA-336.

I looked at the patch and I am really not comfortable with that kind
of change at this stage of the release.

So I'm afraid the answer is no, unless I have misunderstood something.

Regards,
Ian.