| Subject | Re: [PATCH 13/35] autonuma: add page structure fields | From | Peter Zijlstra <> | Date | Tue, 29 May 2012 15:16:25 +0200 |
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On Fri, 2012-05-25 at 19:02 +0200, Andrea Arcangeli wrote:
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 780ded7..e8dc82c 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -126,6 +126,31 @@ struct page { > struct page *first_page; /* Compound tail pages */ > }; > > +#ifdef CONFIG_AUTONUMA > + /* > + * FIXME: move to pgdat section along with the memcg and allocate > + * at runtime only in presence of a numa system. > + */ > + /* > + * To modify autonuma_last_nid lockless the architecture, > + * needs SMP atomic granularity < sizeof(long), not all archs > + * have that, notably some alpha. Archs without that requires > + * autonuma_last_nid to be a long. > + */ > +#if BITS_PER_LONG > 32 > + int autonuma_migrate_nid; > + int autonuma_last_nid; > +#else > +#if MAX_NUMNODES >= 32768 > +#error "too many nodes" > +#endif > + /* FIXME: remember to check the updates are atomic */ > + short autonuma_migrate_nid; > + short autonuma_last_nid; > +#endif > + struct list_head autonuma_migrate_node; > +#endif > + > /* > * On machines where all RAM is mapped into kernel address space, > * we can simply calculate the virtual address. On machines with
24 bytes per page.. or ~0.6% of memory gone. This is far too great a price to pay.
At LSF/MM Rik already suggested you limit the number of pages that can be migrated concurrently and use this to move the extra list_head out of struct page and into a smaller amount of extra structures, reducing the total overhead.
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