f2fs: avoid frequent background GC

If there is no victim segments selected by background GC, let's wait
a little bit longer time to collect dirty segments.
By default, let's give 5 minutes.

Reviewed-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 1ca3324..6ed3263 100644 (file)
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -82,9 +82,6 @@ static int gc_thread_func(void *data)
                /* if return value is not zero, no victim was selected */
                if (f2fs_gc(sbi))
                        wait_ms = GC_THREAD_NOGC_SLEEP_TIME;
-               else if (wait_ms == GC_THREAD_NOGC_SLEEP_TIME)
-                       wait_ms = GC_THREAD_MAX_SLEEP_TIME;
-
        } while (!kthread_should_stop());
        return 0;
 }

diff --git a/fs/f2fs/gc.h b/fs/f2fs/gc.h
index 30b2db0..2c6a6bd 100644 (file)
--- a/fs/f2fs/gc.h
+++ b/fs/f2fs/gc.h
@@ -13,9 +13,9 @@
                                                 * whether IO subsystem is idle
                                                 * or not
                                                 */
-#define GC_THREAD_MIN_SLEEP_TIME       10000 /* milliseconds */
-#define GC_THREAD_MAX_SLEEP_TIME       30000
-#define GC_THREAD_NOGC_SLEEP_TIME      10000
+#define GC_THREAD_MIN_SLEEP_TIME       30000   /* milliseconds */
+#define GC_THREAD_MAX_SLEEP_TIME       60000
+#define GC_THREAD_NOGC_SLEEP_TIME      300000  /* wait 5 min */
 #define LIMIT_INVALID_BLOCK    40 /* percentage over total user space */
 #define LIMIT_FREE_BLOCK       40 /* percentage over invalid + free space */
 
@@ -58,6 +58,9 @@ static inline block_t limit_free_user_blocks(struct f2fs_sb_info *sbi)
 
 static inline long increase_sleep_time(long wait)
 {
+       if (wait == GC_THREAD_NOGC_SLEEP_TIME)
+               return wait;
+
        wait += GC_THREAD_MIN_SLEEP_TIME;
        if (wait > GC_THREAD_MAX_SLEEP_TIME)
                wait = GC_THREAD_MAX_SLEEP_TIME;
@@ -66,6 +69,9 @@ static inline long increase_sleep_time(long wait)
 
 static inline long decrease_sleep_time(long wait)
 {
+       if (wait == GC_THREAD_NOGC_SLEEP_TIME)
+               wait = GC_THREAD_MAX_SLEEP_TIME;
+
        wait -= GC_THREAD_MIN_SLEEP_TIME;
        if (wait <= GC_THREAD_MIN_SLEEP_TIME)
                wait = GC_THREAD_MIN_SLEEP_TIME;