mm: remove per-zone hashtable of bitlock waitqueues

[cascardo/linux.git] / include / linux / mmzone.h

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7f2ae99..0f088f3 100644 (file)
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -440,33 +440,7 @@ struct zone {
        seqlock_t               span_seqlock;
 #endif
 
-       /*
-        * wait_table           -- the array holding the hash table
-        * wait_table_hash_nr_entries   -- the size of the hash table array
-        * wait_table_bits      -- wait_table_size == (1 << wait_table_bits)
-        *
-        * The purpose of all these is to keep track of the people
-        * waiting for a page to become available and make them
-        * runnable again when possible. The trouble is that this
-        * consumes a lot of space, especially when so few things
-        * wait on pages at a given time. So instead of using
-        * per-page waitqueues, we use a waitqueue hash table.
-        *
-        * The bucket discipline is to sleep on the same queue when
-        * colliding and wake all in that wait queue when removing.
-        * When something wakes, it must check to be sure its page is
-        * truly available, a la thundering herd. The cost of a
-        * collision is great, but given the expected load of the
-        * table, they should be so rare as to be outweighed by the
-        * benefits from the saved space.
-        *
-        * __wait_on_page_locked() and unlock_page() in mm/filemap.c, are the
-        * primary users of these fields, and in mm/page_alloc.c
-        * free_area_init_core() performs the initialization of them.
-        */
-       wait_queue_head_t       *wait_table;
-       unsigned long           wait_table_hash_nr_entries;
-       unsigned long           wait_table_bits;
+       int initialized;
 
        /* Write-intensive fields used from the page allocator */
        ZONE_PADDING(_pad1_)
@@ -546,7 +520,7 @@ static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
 
 static inline bool zone_is_initialized(struct zone *zone)
 {
-       return !!zone->wait_table;
+       return zone->initialized;
 }
 
 static inline bool zone_is_empty(struct zone *zone)