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SubjectRe: [patch] mm: shmem: use new radix tree iterator
Hi Hugh,
On 02/04/2013 10:01 AM, Hugh Dickins wrote:
> On Fri, 1 Feb 2013, Johannes Weiner wrote:
>
>> In shmem_find_get_pages_and_swap, use the faster radix tree iterator
>> construct from 78c1d78 "radix-tree: introduce bit-optimized iterator".
>>
>> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
> Yes, that looks fine, and is testing out fine, thanks.
> Acked-by: Hugh Dickins <hughd@google.com>

Could you share your testcase with me? It seems that you always can test
shmem patches.

>
>> ---
>> mm/shmem.c | 25 ++++++++++++-------------
>> 1 file changed, 12 insertions(+), 13 deletions(-)
>>
>> diff --git a/mm/shmem.c b/mm/shmem.c
>> index a368a1c..c5dc8ae 100644
>> --- a/mm/shmem.c
>> +++ b/mm/shmem.c
>> @@ -336,19 +336,19 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
>> pgoff_t start, unsigned int nr_pages,
>> struct page **pages, pgoff_t *indices)
>> {
>> - unsigned int i;
>> - unsigned int ret;
>> - unsigned int nr_found;
>> + void **slot;
>> + unsigned int ret = 0;
>> + struct radix_tree_iter iter;
>> +
>> + if (!nr_pages)
>> + return 0;
>>
>> rcu_read_lock();
>> restart:
>> - nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
>> - (void ***)pages, indices, start, nr_pages);
>> - ret = 0;
>> - for (i = 0; i < nr_found; i++) {
>> + radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
>> struct page *page;
>> repeat:
>> - page = radix_tree_deref_slot((void **)pages[i]);
>> + page = radix_tree_deref_slot(slot);
>> if (unlikely(!page))
>> continue;
>> if (radix_tree_exception(page)) {
>> @@ -365,17 +365,16 @@ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
>> goto repeat;
>>
>> /* Has the page moved? */
>> - if (unlikely(page != *((void **)pages[i]))) {
>> + if (unlikely(page != *slot)) {
>> page_cache_release(page);
>> goto repeat;
>> }
>> export:
>> - indices[ret] = indices[i];
>> + indices[ret] = iter.index;
>> pages[ret] = page;
>> - ret++;
>> + if (++ret == nr_pages)
>> + break;
>> }
>> - if (unlikely(!ret && nr_found))
>> - goto restart;
>> rcu_read_unlock();
>> return ret;
>> }
>> --
>> 1.7.11.7
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