Re: [patch][rfc] 2.6.23-rc1 mm: NUMA replicated pagecache

Nick Piggin
2007-07-30T03:16:25Z

On Fri, Jul 27, 2007 at 10:30:47AM -0400, Lee Schermerhorn wrote:
> On Fri, 2007-07-27 at 10:42 +0200, Nick Piggin wrote:
> > Hi,
> >
> > Just got a bit of time to take another look at the replicated pagecache
> > patch. The nopage vs invalidate race and clear_page_dirty_for_io fixes
> > gives me more confidence in the locking now; the new ->fault API makes
> > MAP_SHARED write faults much more efficient; and a few bugs were found
> > and fixed.
> >
> > More stats were added: *repl* in /proc/vmstat. Survives some kbuilding
> > tests...
> >
> > --
> >
> > Page-based NUMA pagecache replication.
> <snip really big patch!>
>
> Hi, Nick.
>
> Glad to see you're back on this. It's been on my list, but delayed by
> other patch streams...

Yeah, thought I should keep it alive :) Patch is against 2.6.23-rc1.

> As I mentioned to you in prior mail, I want to try to integrate this
> atop my "auto/lazy migration" patches, such that when a task moves to a
> new node, we remove just that task's pte ref's to page cache pages
> [along with all refs to anon pages, as I do now] so that the task will
> take a fault on next touch and either use an existing local copy or
> replicate the page at that time. Unfortunately, that's in the queue
> behind the memoryless node patches and my stalled shared policy patches,
> among other things :-(.

That's OK. It will likely be a long process to get any of this in...
As you know, replicated currently needs some of your automigration
infrastructure in order to get ptes pointing to the right places
after a task migration. I'd like to try some experiments with them on
a larger system, once you get time to update your patchset...

Thanks,
Nick