Re: Minutes from Feb 21 LSE Call

Andrea Arcangeli
2003-02-25T17:48:59Z

On Tue, Feb 25, 2003 at 09:43:59AM -0800, William Lee Irwin III wrote:
> On Sat, Feb 22, 2003 at 07:24:24PM -0800, Andrew Morton wrote:
> >> So whole stole the remaining 1.85 seconds? Looks like pte_highmem.
>
> On Tue, Feb 25, 2003 at 06:17:27PM +0100, Andrea Arcangeli wrote:
> > would you mind to add the line for 2.4.21-pre4aa3? it has pte-highmem so
> > you can easily find it out for sure if it is pte_highmem that stole >10%
> > of your fast cpu. A line for the 2.4-rmap patch would be also
> > interesting.
>
> On Sat, Feb 22, 2003 at 07:24:24PM -0800, Andrew Morton wrote:
> >> Note one second spent in pte_alloc_one().
>
> On Tue, Feb 25, 2003 at 06:17:27PM +0100, Andrea Arcangeli wrote:
> > note the seconds spent in the rmap affected paths too.
>
> The pagetable cache is gone in 2.5, so pte_alloc_one() takes the
> bitblitting hit for pagetables.

I'm talking about do_anonymous_page, do_wp_page, do_no_page fork and all
the other places that introduces spinlocks (per-page) and allocations of
2 pieces of ram rather than just 1 (and in turn potentially global
spinlocks too if the cpu-caches are empty). Just grep for
pte_chain_alloc or page_add_rmap in mm/memory.c, that's what I mean, I'm
not talking about pagetables.

Andrea