Re: [Xen-devel] Is that possible to merge MBA into Xen 4.10?

[Lars Kurth <lars.kurth.xen@xxxxxxxxx>]

Hi all,

> On 24 Oct 2017, at 09:35, Jan Beulich <jbeulich@xxxxxxxx> wrote:
> 
>>>> On 24.10.17 at 04:10, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> As you may know, MBA patch set has got enough Reviewed-by/Acked-by in last 
>> week.
>> It is ready to be merged. 
>> 
>> This is a feature for Skylake, Intel has launched Skylake and KVM already
>> supported MBA, so including it in Xen 4.10 will quickly fill this gap.
>> 
>> MBA missed the 4.10 feature freeze date for only a few days due to lack of
>> timely review for earlier versions which slowed down the patch iteration 
>> notably.
>> It seems maintainers are very busy recently so that the review progress for 
>> 4.10
>> is slower than before. So I am wondering if it is possible to merge it into 
>> 4.10?
>> 
>> This patch set mainly touches codes related to PSR in 
>> tools/domctl/sysctl/hypervisor.
>> It does not touch other features. So, the risk is low to merge it.
> 
> While I agree the risk is low, I think we should not start making
> exceptions from the "no freeze exceptions" rule. Even less so
> for a secondary (or should I pull out my favorite "niche" again?)
> feature like this one. But in the end it's Julien's call., of course.

I think there are a number of separate issues concerns, which are somewhat 
orthogonal:

a) Sticking to the rules
I think in some cases where a few days have been missed, we should have enough 
flexibility to bend the rules.
In fact, if say a crucial part of PVHv2 missed the deadline by a few days, we 
would probably bend the rules. 

Of course whether something is a "niche" feature is in view of the beholder.

b) Risk 
This is something which is clearly important.

c) PR Perspective
I am somewhat concerned that we do not have a lot of stuff for good media 
coverage for Xen 4.10

This is a relatively small release: from what I can see we have approximately 
only around 235 patch series (4.9 had 481, 4.8 had 575)
Admittedly the number of patches in 4.10 is quite high: approx 1707 patches 
(with 1549 in 4.9 and 1245 in 4.8)
A lot of it seems to be groundwork for 4.11 (or even 4.12)

Besides PVHv2, we don't have a lot of big marketable new stuff which would 
enable us to get press quotes. 
Admittedly, I have not put a list of marketable features together yet.
A feature such as MBA, would help from a PR perspective.


But ultimately this is going to be Julien's call.

Regards
Lars
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