Re: [Patch v3 0/7] Optimize clear dirty log

Sean Christopherson
2023-03-21T00:41:27Z

On Fri, Mar 17, 2023, Sean Christopherson wrote:
> On Fri, Feb 10, 2023, Vipin Sharma wrote:
> > This patch series has optimized control flow of clearing dirty log and
> > improved its performance by ~40% (2% more than v2).
> >
> > It also got rid of many variants of the handle_changed_spte family of
> > functions and converged logic to one handle_changed_spte() function. It
> > also remove tdp_mmu_set_spte_no_[acc_track|dirty_log] and various
> > booleans for controlling them.
> >
> > v3:
> > - Tried to do better job at writing commit messages.
>
> LOL, that's the spirit!
>
> Did a cursory glance, looks good. I'll do a more thorough pass next week and get
> it queued up if all goes well. No need for a v4 at this point, I'll fixup David's
> various nits when applying.

Ooof, that ended up being painful. In hindsight, I should have asked for a v4,
but damage done, and it's my fault for throwing you a big blob of code in the
first place.

I ended up splitting the "interesting" patches into three each:

1. Switch to the atomic-AND
2. Drop the access-tracking / dirty-logging (as appropriate)
3. Drop the call to __handle_changed_spte()

because logically they are three different things (although obviously related).

I have pushed the result to kvm-x86/mmu, but haven't merged to kvm-x86/next or
sent thanks because it's not yet tested. I'll do testing tomorrow, but if you
can take a look in the meantime to make sure I didn't do something completely
boneheaded, it'd be much appreciated.