Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

Matt Mackall
2007-07-19T01:29:25Z

On Thu, Jul 19, 2007 at 02:48:37AM +0200, Rene Herman wrote:
> On 07/19/2007 02:41 AM, Matt Mackall wrote:
>
> >On Thu, Jul 19, 2007 at 02:15:39AM +0200, Andrea Arcangeli wrote:
>
> >>Using kmalloc(8k) instead of alloc_page() doesn't sound a too big deal
> >>and that will solve the problem.
> >
> >How do you figure?
> >
> >If you're saying that soft pages helps our 8k stack allocations, it
> >doesn't. The memory overhead of soft pages will be higher (5-15%,
> >mostly due to file tails in pagecache) than the level at which 8k
> >stacks currently run into trouble (1-2% free?).
> >
> >Not helpful.
>
> With tail-packing it is.

Tail packing is a whole new can of worms. Especially as it's very
likely to make performance suffer on small files (the common case).

On the other hand, if someone can demonstrate that tail-packed page
cache doesn't suck, we should put it in mainline pronto. The poor
architectures that are stuck with real 64k pages are sure to
appreciate it.

--
Mathematics is the supreme nostalgia of our time.