md: reduce CPU wastage on idle md array with a write-intent bitmap

[linux-2.6-omap-h63xx.git] / drivers / md / bitmap.c

diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c
index 7aeceedcf7d46de93824a14ce9b93888350930dd..831aed9c56ffce68384365f95b432634ababa6f3 100644 (file)
--- a/drivers/md/bitmap.c
+++ b/drivers/md/bitmap.c
@@ -1047,6 +1047,11 @@ void bitmap_daemon_work(struct bitmap *bitmap)
        if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ))
                return;
        bitmap->daemon_lastrun = jiffies;
+       if (bitmap->allclean) {
+               bitmap->mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT;
+               return;
+       }
+       bitmap->allclean = 1;
 
        for (j = 0; j < bitmap->chunks; j++) {
                bitmap_counter_t *bmc;
@@ -1068,8 +1073,10 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                                        clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE);
 
                                spin_unlock_irqrestore(&bitmap->lock, flags);
-                               if (need_write)
+                               if (need_write) {
                                        write_page(bitmap, page, 0);
+                                       bitmap->allclean = 0;
+                               }
                                continue;
                        }
 
@@ -1098,6 +1105,9 @@ void bitmap_daemon_work(struct bitmap *bitmap)
 /*
   if (j < 100) printk("bitmap: j=%lu, *bmc = 0x%x\n", j, *bmc);
 */
+                       if (*bmc)
+                               bitmap->allclean = 0;
+
                        if (*bmc == 2) {
                                *bmc=1; /* maybe clear the bit next time */
                                set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
@@ -1132,6 +1142,8 @@ void bitmap_daemon_work(struct bitmap *bitmap)
                }
        }
 
+       if (bitmap->allclean == 0)
+               bitmap->mddev->thread->timeout = bitmap->daemon_sleep * HZ;
 }
 
 static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap,
@@ -1226,6 +1238,7 @@ int bitmap_startwrite(struct bitmap *bitmap, sector_t offset, unsigned long sect
                        sectors -= blocks;
                else sectors = 0;
        }
+       bitmap->allclean = 0;
        return 0;
 }
 
@@ -1296,6 +1309,7 @@ int bitmap_start_sync(struct bitmap *bitmap, sector_t offset, int *blocks,
                }
        }
        spin_unlock_irq(&bitmap->lock);
+       bitmap->allclean = 0;
        return rv;
 }
 
@@ -1332,6 +1346,7 @@ void bitmap_end_sync(struct bitmap *bitmap, sector_t offset, int *blocks, int ab
        }
  unlock:
        spin_unlock_irqrestore(&bitmap->lock, flags);
+       bitmap->allclean = 0;
 }
 
 void bitmap_close_sync(struct bitmap *bitmap)
@@ -1399,7 +1414,7 @@ static void bitmap_set_memory_bits(struct bitmap *bitmap, sector_t offset, int n
                set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN);
        }
        spin_unlock_irq(&bitmap->lock);
-
+       bitmap->allclean = 0;
 }
 
 /* dirty the memory and file bits for bitmap chunks "s" to "e" */