[RFC][patch] mem_notify more faster reduce load average

[KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>]

Hi, Marcelo-san

this patch is a bit improvement against my mem notifications large system patch.
original my patch is too slower reduce load average at after free memory increased.
this patch fixed it.



Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Index: linux-2.6.23-mem_notify_v3/mm/mem_notify.c
===================================================================
--- linux-2.6.23-mem_notify_v3.orig/mm/mem_notify.c
+++ linux-2.6.23-mem_notify_v3/mm/mem_notify.c
@@ -20,7 +20,8 @@ struct mem_notify_file_info {
         long          last_event;
 };

-atomic_t mem_notify_event = ATOMIC_INIT(0);
+static atomic_t mem_notify_event = ATOMIC_INIT(0);
+static atomic_t mem_notify_event_end = ATOMIC_INIT(0);

 static DECLARE_WAIT_QUEUE_HEAD(mem_wait);
 static atomic_long_t last_mem_notify = ATOMIC_LONG_INIT(INITIAL_JIFFIES);
@@ -76,13 +77,18 @@ static unsigned int mem_notify_poll(stru
        unsigned long bonus;
        unsigned long now;
        unsigned long last;
+       unsigned long event;

        poll_wait(file, &mem_wait, wait);

-        if (file_info->last_event == atomic_read(&mem_notify_event))
+retry:
+       event = atomic_read(&mem_notify_event);
+       if (event == file_info->last_event)
                 goto out;

-retry:
+       if (event == atomic_read(&mem_notify_event_end))
+               goto out;
+
        /* Ugly trick:
           when too many task wakeup,
           control function exit rate for prevent too much freed.
@@ -114,6 +120,8 @@ retry:

        if (pages_free < (pages_high+pages_reserve)*2)
                val = POLLIN;
+       else
+               atomic_set(&mem_notify_event_end, event);

 out:



- kosaki




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