Re: What was the problem with quicklists and x86-64?

Christoph Lameter
2007-12-13T20:53:27Z

On Fri, 14 Dec 2007, Benjamin Herrenschmidt wrote:

> > These issues only exist with NUMA because of the freeing of off node pages
> > before the TLB flush was done. There was a discussion about this issue and
> > my fix of simply not freeing the offnode pages early was ignored. Instead
> > the x86_64 implementation (which has no problems that I know of) was
> > pulled leaving the issue open in the core. Benjamin Herrrenschmidt
> > wanted to take a look at these issues (CCing him).
>
> I don't know how NUMA gets in the picture there, it's probably very x86
> specific thing. The issue we have here happens on other platforms
> unrelated to NUMA. The fact that is tired to NUMA on x86 might be due to
> the way the HW tablewalk operates on these.

This is a generic NUMA issue here! Quicklist pages that are not on
the current node are freed without waiting for the TLB flush. The patch
that I posted fixes that by requiring that all pages be flushed.