Resend.
he patch is based on mmotm-2011-02-04 +
mm-add-replace_page_cache_page-function-add-freepage-hook.patch.
On Fri, Feb 11, 2011 at 01:33:46AM +0900, Minchan Kim wrote:
> This patch optmizes replace_page_cache_page.
>
> 1) remove radix_tree_preload
> 2) single radix_tree_lookup_slot and replace radix tree slot
> 3) page accounting optimization if both pages are in same zone.
>
> Cc: Miklos Szeredi <mszeredi@xxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Cc: Mel Gorman <mel@xxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> ---
> mm/filemap.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++---------
> 1 files changed, 51 insertions(+), 10 deletions(-)
>
> Hi Miklos,
> This patch is totally not tested.
> Could you test this patch?
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index a25c898..918ef1e 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -148,6 +148,56 @@ void __remove_from_page_cache(struct page *page)
> }
> }
>
> +/*
> + * Replace a page from the page cache with a new one.
> + * Both the old and new page must be locked.
> + * The caller must hold the mapping's tree_lock.
> + */
> +void __replace_page_cache_page(struct page *old, struct page *new)
> +{
> + void **pslot;
> + struct address_space *mapping = old->mapping;
> + struct zone *old_zone, *new_zone;
> +
> + old_zone = page_zone(old);
> + new_zone = page_zone(new);
> + /*
> + * if we're uptodate, flush out into the cleancache, otherwise
> + * invalidate any existing cleancache entries. We can't leave
> + * stale data around in the cleancache once our page is gone
> + */
> + if (PageUptodate(old))
> + cleancache_put_page(old);
> + else
> + cleancache_flush_page(mapping, old);
> +
> + pslot = radix_tree_lookup_slot(&mapping->page_tree,
> + page_index(old));
> + get_page(new); /* add cache reference */
> + radix_tree_replace_slot(pslot, new);
> + old->mapping = NULL;
> + if (old_zone != new_zone) {
> + __dec_zone_page_state(old, NR_FILE_PAGES);
> + __inc_zone_page_state(new, NR_FILE_PAGES);
> + if (PageSwapBacked(old)) {
> + __dec_zone_page_state(old, NR_SHMEM);
> + __inc_zone_page_state(new, NR_SHMEM);
> + }
> + }
> + BUG_ON(page_mapped(old));
> + /*
> + * Some filesystems seem to re-dirty the page even after
> + * the VM has canceled the dirty bit (eg ext3 journaling).
> + *
> + * Fix it up by doing a final dirty accounting check after
> + * having removed the page entirely.
> + */
> + if (PageDirty(old) && mapping_cap_account_dirty(mapping)) {
> + dec_zone_page_state(old, NR_FILE_DIRTY);
> + dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
> + }
> +}
> +
> void remove_from_page_cache(struct page *page)
> {
> struct address_space *mapping = page->mapping;
> @@ -433,7 +483,6 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
> if (error)
> return error;
>
> - error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
> if (!error) {
> struct address_space *mapping = old->mapping;
> void (*freepage)(struct page *);
> @@ -441,20 +490,12 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
> pgoff_t offset = old->index;
> freepage = mapping->a_ops->freepage;
>
> - page_cache_get(new);
> new->mapping = mapping;
> new->index = offset;
>
> spin_lock_irq(&mapping->tree_lock);
> - __remove_from_page_cache(old);
> - error = radix_tree_insert(&mapping->page_tree, offset, new);
> - BUG_ON(error);
> - mapping->nrpages++;
> - __inc_zone_page_state(new, NR_FILE_PAGES);
> - if (PageSwapBacked(new))
> - __inc_zone_page_state(new, NR_SHMEM);
> + __replace_page_cache_page(old, new);
> spin_unlock_irq(&mapping->tree_lock);
> - radix_tree_preload_end();
> if (freepage)
> freepage(old);
> page_cache_release(old);
> --
> 1.7.1
>
--
Kind regards,
Minchan Kim
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