Re: [PATCH] pvclock: introduce seqcount-like API

From: Paolo Bonzini
Date: Thu Jun 09 2016 - 14:03:13 EST




On 09/06/2016 19:12, Andy Lutomirski wrote:
> On Thu, Jun 9, 2016 at 6:45 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>> On 09/06/2016 15:35, Roman Kagan wrote:
>>> On Thu, Jun 09, 2016 at 02:47:54PM +0200, Paolo Bonzini wrote:
>>>> On 09/06/2016 14:43, Roman Kagan wrote:
>>> Has it landed in any public tree? I'm unable to find any. There
>>> appears to be another version of the patch on the list, so I'm confused.
>>
>> I'm about to push it to kvm/master.
>
> Sorry for being slow. I'm catching up. In its current form, I don't
> like this patch. Please don't apply it.

Sure, I was talking about Minfei's patches, not this one. :) Of course
I need ack for this one.

> The problem is that this makes two significant changes at once:
>
> 1. Use the new version helpers. I like that change.
>
> 2. Use __pvclock_read_cycles. That should be separate, and it should
> come with timing numbers in the changelog.

__pvclock_read_cycles is pretty much the same as the code that is being
inlined. Thus the only change is that __pvclock_read_cycles is called
inside the loop rather than outside, but the loop really is expected to
never roll so why make a copy in the first place?

I'll split the patch anyway, thanks!

Paolo