Re: [RFC 00/10] x86 TLB flush cleanups, moving toward PCID support

[Ingo Molnar]

* Andy Lutomirski <luto@xxxxxxxxxx> wrote:

> As I've been working on polishing my PCID code, a major problem I've
> encountered is that there are too many x86 TLB flushing code paths and
> that they have too many inconsequential differences.  The result was
> that earlier versions of the PCID code were a colossal mess and very
> difficult to understand.
> 
> This series goes a long way toward cleaning up the mess.  With all the
> patches applied, there is a single function that contains the meat of
> the code to flush the TLB on a given CPU, and all the tlb flushing
> APIs call it for both local and remote CPUs.
> 
> This series should only adversely affect the kernel in a couple of
> minor ways:
> 
>  - It makes smp_mb() unconditional when flushing TLBs.  We used to
>    use the TLB flush itself to mostly avoid smp_mb() on the initiating
>    CPU.
> 
>  - On UP kernels, we lose the dubious optimization of inlining nerfed
>    variants of all the TLB flush APIs.  This bloats the kernel a tiny
>    bit, although it should increase performance, since the SMP
>    versions were better.
> 
> Patch 10 in here is a little bit off topic.  It's a cleanup that's
> also needed before PCID can go in, but it's not directly about
> TLB flushing.
> 
> Thoughts?

Looks really nifty! The diffstat alone appears to be worth it:

 18 files changed, 334 insertions(+), 408 deletions(-)

Will have a closer look next week.

Thanks,

	Ingo