Re: [Xen-devel] [PATCH v9] new config option vtsc_tolerance_khz to avoid TSC emulation

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 10/01/2018 12:25 PM, Jan Beulich wrote:
>>>> On 01.10.18 at 12:52, <ian.jackson@xxxxxxxxxx> wrote:
>> Olaf Hering writes ("Re: [PATCH v9] new config option vtsc_tolerance_khz to 
>> avoid TSC emulation"):
>>> Am Thu, 13 Sep 2018 09:39:13 +0200
>>> schrieb Olaf Hering <olaf@xxxxxxxxx>:
>>>> this patch was not applied yet, even after a few "pings".
>>>
>>> No reaction since months.
>>> So scrap that patch, just in case it is still part of someones to-consider 
>> queue.
>>
>> I think it would be worth exploring whether this patch could be
>> applied without an explicit ack from Andrew.
>>
>> I confess I ignored all the previous mails because they all started
>>    Andrew,
>> or
>>    Andrew, Lars,
>> so I assumed that you didn't want attention from other
>> maintainers/committers.
>>
>> Now that I look at the thread it is difficult for me to see the wood
>> for the trees but I don't see unanswered concerns.
> 
> Problem is - discussion around this was (iirc) happening not only on
> the list, but also on irc (including perhaps private chats). It was for
> that reason that I made my R-b conditional upon Andrew at least
> giving an informal go-ahead (otherwise, together with Wei's R-b,
> the patch could have gone in).
> 
> Besides the question of correctness from the perspective of guests
> (which imo is not a problem as the feature needs to be actively
> enabled, and I think we have no reason to keep admins from
> breaking their guests if they really mean to), 

I agree with this, BTW.

> I think the main concern
> was with the way migration of the new value was implemented. But I
> really have to defer to Andrew for that, irrespective of him not
> having responded (on the list) to prior pings.

Is Andrew really the only person who knows enough about migration to
give this the thumbs-up?  Technically migration is in the toolstack, and
so Wei should have double-checked that before giving his review; and
when a question was raised, Wei (as the relevant maintainer who had
given it an R-b) should either have asserted that the code was indeed
correct, or withdrawn his R-b and given Olaf feedback to allow him to
get it into shape.

(This is all based on the history sketched out by Jan above; if there is
more to it then of course this analysis may not be correct.)

I was only skimming the thread, and intended to weigh in at some point;
but I didn't really understand why it was blocked on Andrew in the first
place.

 -George

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