Page allocator: clean up pcp draining functions

- Add comments explaing how drain_pages() works.

- Eliminate useless functions

- Rename drain_all_local_pages to drain_all_pages(). It does drain
  all pages not only those of the local processor.

- Eliminate useless interrupt off / on sequences. drain_pages()
  disables interrupts on its own. The execution thread is
  pinned to processor by the caller. So there is no need to
  disable interrupts.

- Put drain_all_pages() declaration in gfp.h and remove the
  declarations from suspend.h and from mm/memory_hotplug.c

- Make software suspend call drain_all_pages(). The draining
  of processor local pages is may not the right approach if
  software suspend wants to support SMP. If they call drain_all_pages
  then we can make drain_pages() static.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Daniel Walker <dwalker@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 7e93a9ae7064c3a59b0223763964181500f6d3cf..0c6ce515185d24f32476a1b4ebec353be36419bd 100644 (file)
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -228,5 +228,7 @@ extern void FASTCALL(free_cold_page(struct page *page));
 
 void page_alloc_init(void);
 void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp);
+void drain_all_pages(void);
+void drain_local_pages(void *dummy);
 
 #endif /* __LINUX_GFP_H */

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 646ce2d068d4398b13c3a31d61e2350c14ab355a..1d7d4c5797ee93c37ab2d7f035f26fa114649a3f 100644 (file)
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -130,7 +130,6 @@ struct pbe {
 };
 
 /* mm/page_alloc.c */
-extern void drain_local_pages(void);
 extern void mark_free_pages(struct zone *zone);
 
 /**

diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index f6a5df934f8d40848fb5ac8487b81560e29742c9..95250d7c8d91db36593fc3707b10c99a8370dc62 100644 (file)
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -1203,7 +1203,7 @@ asmlinkage int swsusp_save(void)
 
        printk(KERN_INFO "PM: Creating hibernation image: \n");
 
-       drain_local_pages();
+       drain_local_pages(NULL);
        nr_pages = count_data_pages();
        nr_highmem = count_highmem_pages();
        printk(KERN_INFO "PM: Need to copy %u pages\n", nr_pages + nr_highmem);
@@ -1221,7 +1221,7 @@ asmlinkage int swsusp_save(void)
        /* During allocating of suspend pagedir, new cold pages may appear.
         * Kill them.
         */
-       drain_local_pages();
+       drain_local_pages(NULL);
        copy_data_pages(&copy_bm, &orig_bm);
 
        /*

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9512a544d0449ebcb789de665d9e8fc8ee0fdc8b..7469c503580dcf6402000cc339359175a9b417fc 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -481,8 +481,6 @@ check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
        return offlined;
 }
 
-extern void drain_all_local_pages(void);
-
 int offline_pages(unsigned long start_pfn,
                  unsigned long end_pfn, unsigned long timeout)
 {
@@ -540,7 +538,7 @@ repeat:
                lru_add_drain_all();
                flush_scheduled_work();
                cond_resched();
-               drain_all_local_pages();
+               drain_all_pages();
        }
 
        pfn = scan_lru_pages(start_pfn, end_pfn);
@@ -563,7 +561,7 @@ repeat:
        flush_scheduled_work();
        yield();
        /* drain pcp pages , this is synchrouns. */
-       drain_all_local_pages();
+       drain_all_pages();
        /* check again */
        offlined_pages = check_pages_isolated(start_pfn, end_pfn);
        if (offlined_pages < 0) {

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b2838c24e582c11b8e0680ca5d5b5f97389145ba..5c7de8e959fc1485f7253972a922e90d5587ef1f 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -890,7 +890,14 @@ void drain_zone_pages(struct zone *zone, struct per_cpu_pages *pcp)
 }
 #endif
 
-static void __drain_pages(unsigned int cpu)
+/*
+ * Drain pages of the indicated processor.
+ *
+ * The processor must either be the current processor and the
+ * thread pinned to the current processor or a processor that
+ * is not online.
+ */
+static void drain_pages(unsigned int cpu)
 {
        unsigned long flags;
        struct zone *zone;
@@ -915,6 +922,22 @@ static void __drain_pages(unsigned int cpu)
        }
 }
 
+/*
+ * Spill all of this CPU's per-cpu pages back into the buddy allocator.
+ */
+void drain_local_pages(void *arg)
+{
+       drain_pages(smp_processor_id());
+}
+
+/*
+ * Spill all the per-cpu pages from all CPUs back into the buddy allocator
+ */
+void drain_all_pages(void)
+{
+       on_each_cpu(drain_local_pages, NULL, 0, 1);
+}
+
 #ifdef CONFIG_HIBERNATION
 
 void mark_free_pages(struct zone *zone)
@@ -951,37 +974,6 @@ void mark_free_pages(struct zone *zone)
 }
 #endif /* CONFIG_PM */
 
-/*
- * Spill all of this CPU's per-cpu pages back into the buddy allocator.
- */
-void drain_local_pages(void)
-{
-       unsigned long flags;
-
-       local_irq_save(flags);  
-       __drain_pages(smp_processor_id());
-       local_irq_restore(flags);       
-}
-
-void smp_drain_local_pages(void *arg)
-{
-       drain_local_pages();
-}
-
-/*
- * Spill all the per-cpu pages from all CPUs back into the buddy allocator
- */
-void drain_all_local_pages(void)
-{
-       unsigned long flags;
-
-       local_irq_save(flags);
-       __drain_pages(smp_processor_id());
-       local_irq_restore(flags);
-
-       smp_call_function(smp_drain_local_pages, NULL, 0, 1);
-}
-
 /*
  * Free a 0-order page
  */
@@ -1569,7 +1561,7 @@ nofail_alloc:
        cond_resched();
 
        if (order != 0)
-               drain_all_local_pages();
+               drain_all_pages();
 
        if (likely(did_some_progress)) {
                page = get_page_from_freelist(gfp_mask, order,
@@ -3978,10 +3970,23 @@ static int page_alloc_cpu_notify(struct notifier_block *self,
        int cpu = (unsigned long)hcpu;
 
        if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
-               local_irq_disable();
-               __drain_pages(cpu);
+               drain_pages(cpu);
+
+               /*
+                * Spill the event counters of the dead processor
+                * into the current processors event counters.
+                * This artificially elevates the count of the current
+                * processor.
+                */
                vm_events_fold_cpu(cpu);
-               local_irq_enable();
+
+               /*
+                * Zero the differential counters of the dead processor
+                * so that the vm statistics are consistent.
+                *
+                * This is only okay since the processor is dead and cannot
+                * race with what we are doing.
+                */
                refresh_cpu_vm_stats(cpu);
        }
        return NOTIFY_OK;
@@ -4480,7 +4485,7 @@ int set_migratetype_isolate(struct page *page)
 out:
        spin_unlock_irqrestore(&zone->lock, flags);
        if (!ret)
-               drain_all_local_pages();
+               drain_all_pages();
        return ret;
 }