[PATCH v2] [mmotm] trace bio queueing trial only when it occurs
From: Minchan Kim
Date: Tue Sep 08 2009 - 03:50:00 EST
* Add history that why it is breaked in changelog.
Thanks for careful review, Wu, Li.
== CUT_HERE ==
If BIO is discarded or cross over end of device,
BIO queueing trial doesn't occur.
Actually the trace was called just before make_request at first:
[PATCH] Block queue IO tracing support (blktrace) as of 2006-03-23
  Â2056a782f8e7e65fd4bfd027506b4ce1c5e9ccd4
And then 2 patches added some checks between them:
[PATCH] md: check bio address after mapping through partitions
   Â5ddfe9691c91a244e8d1be597b6428fcefd58103,
[BLOCK] Don't allow empty barriers to be passed down to
queues that don't grok them
   Â51fd77bd9f512ab6cc9df0733ba1caaab89eb957
It breaks original goal.
Let's trace it only when it happens.
Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
Acked-by: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
---
block/blk-core.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/block/blk-core.c b/block/blk-core.c
index 5b59592..1a0cfd5 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -1463,8 +1463,6 @@ static inline void __generic_make_request(struct bio *bio)
if (old_sector != -1)
trace_block_remap(q, bio, old_dev, old_sector);
- trace_block_bio_queue(q, bio);
-
old_sector = bio->bi_sector;
old_dev = bio->bi_bdev->bd_dev;
@@ -1477,6 +1475,8 @@ static inline void __generic_make_request(struct bio *bio)
goto end_io;
}
+ trace_block_bio_queue(q, bio);
+
ret = q->make_request_fn(q, bio);
} while (ret);
--
1.6.4
--
Kind regards,
Minchan Kim
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