On 2015/10/6 6:43, Jaegeuk Kim wrote:
This patch introduces a tracepoint to monitor background gc behaviors.
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/f2fs/gc.c | 3 +++
include/trace/events/f2fs.h | 28 ++++++++++++++++++++++++++++
2 files changed, 31 insertions(+)
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index e627c19..e7cec86 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -77,6 +77,9 @@ static int gc_thread_func(void *data)
stat_inc_bggc_count(sbi);
+ trace_f2fs_background_gc(sbi->sb, wait_ms,
+ prefree_segments(sbi), free_segments(sbi));
+
/* if return value is not zero, no victim was selected */
if (f2fs_gc(sbi, test_opt(sbi, FORCE_FG_GC)))
wait_ms = gc_th->no_gc_sleep_time;
diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
index 6aa63d9..7de751d 100644
--- a/include/trace/events/f2fs.h
+++ b/include/trace/events/f2fs.h
@@ -514,6 +514,34 @@ TRACE_EVENT(f2fs_map_blocks,
__entry->ret)
);
+TRACE_EVENT(f2fs_background_gc,
+
+ TP_PROTO(struct super_block *sb, long wait_ms,
+ unsigned int prefree, unsigned int free),
+
+ TP_ARGS(sb, wait_ms, prefree, free),
+
+ TP_STRUCT__entry(
+ __field(dev_t, dev)
+ __field(long, wait_ms)
+ __field(unsigned int, prefree)
+ __field(unsigned int, free)
+ ),
+
+ TP_fast_assign(
+ __entry->dev = sb->s_dev;
+ __entry->wait_ms = wait_ms;
+ __entry->prefree = prefree;
+ __entry->free = free;
+ ),
+
+ TP_printk("dev = (%d,%d), wait_ms = %ld, prefree = %u, free = %u",
+ show_dev(__entry),
+ __entry->wait_ms,
+ __entry->prefree,
+ __entry->free)
+);
+
hi,
I open f2fs_background_gc and f2fs_get_victim trace points, first, the partition has no dirty segment, so no victim is
selected, wait_ms is equal to 300s.
f2fs_gc-8:33-2827 [001] .... 5014.608396: f2fs_background_gc: dev = (8,33), wait_ms = 300000, prefree = 0, free = 73
f2fs_gc-8:33-2827 [000] .... 5314.793436: f2fs_background_gc: dev = (8,33), wait_ms = 300000, prefree = 0, free = 73
then I made the partition satisfied the condition of has_enough_invalid_blocks, gc can get a victim and do garbage collection, wait_ms = 30s
f2fs_gc-8:33-2827 [001] .... 5614.978486: f2fs_background_gc: dev = (8,33), wait_ms = 30000, prefree = 0, free = 54
f2fs_gc-8:33-2827 [001] .... 5614.978538: f2fs_get_victim: dev = (8,33), type = No TYPE, policy = (Background GC, LFS-mode, Cost-Benefit), victim = 441 ofs_unit = 1, pre_victim_secno = -1, prefree = 0, free = 54
f2fs_gc-8:33-2827 [000] .... 5644.996989: f2fs_background_gc: dev = (8,33), wait_ms = 30000, prefree = 0, free = 54
f2fs_gc-8:33-2827 [000] .... 5644.997027: f2fs_get_victim: dev = (8,33), type = No TYPE, policy = (Background GC, LFS-mode, Cost-Benefit), victim = 97 ofs_unit = 1, pre_victim_secno = -1, prefree = 0, free = 54
when there no dirty segments left, I think wait_ms could turn back to 300s
f2fs_gc-8:33-2827 [000] .... 6305.596205: f2fs_background_gc: dev = (8,33), wait_ms = 30000, prefree = 1, free = 64
f2fs_gc-8:33-2827 [001] .... 6605.781281: f2fs_background_gc: dev = (8,33), wait_ms = 30000, prefree = 0, free = 65
f2fs_gc-8:33-2827 [000] .... 6905.966301: f2fs_background_gc: dev = (8,33), wait_ms = 30000, prefree = 0, free = 65
f2fs_gc-8:33-2827 [001] .... 7206.151344: f2fs_background_gc: dev = (8,33), wait_ms = 30000, prefree = 0, free = 65
here, background gc triggers every 300s, but wait_ms is still 30s, I don't know why?
Best wishes,
Thanks
TRACE_EVENT(f2fs_get_victim,
TP_PROTO(struct super_block *sb, int type, int gc_type,
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