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Subject[PATCH] blktrace: Use rq->cmd_flags directly in blk_add_trace_rq.
Date
From: Tao Ma <boyu.mt@taobao.com>

In blk_add_trace_rq, we only chose the minor 2 bits from
request's cmd_flags and did some check for discard.
so most of other flags(e.g, REQ_SYNC) are missing.

For example, with a sync write after blkparse we get:
8,16 1 1 0.001776503 7509 A WS 1349632 + 1024 <- (8,17) 1347584
8,16 1 2 0.001776813 7509 Q WS 1349632 + 1024 [dd]
8,16 1 3 0.001780395 7509 G WS 1349632 + 1024 [dd]
8,16 1 5 0.001783186 7509 I W 1349632 + 1024 [dd]
8,16 1 11 0.001816987 7509 D W 1349632 + 1024 [dd]
8,16 0 2 0.006218192 0 C W 1349632 + 1024 [0]

Since now we have integrated the flags of both bio and request,
it is safe to pass rq->cmd_flags directly to __blk_add_trace.

With this patch, after a sync write we get:
8,16 1 1 0.001776900 5425 A WS 1189888 + 1024 <- (8,17) 1187840
8,16 1 2 0.001777179 5425 Q WS 1189888 + 1024 [dd]
8,16 1 3 0.001780797 5425 G WS 1189888 + 1024 [dd]
8,16 1 5 0.001783402 5425 I WS 1189888 + 1024 [dd]
8,16 1 11 0.001817468 5425 D WS 1189888 + 1024 [dd]
8,16 0 2 0.005640709 0 C WS 1189888 + 1024 [0]

Cc: Jens Axboe <jaxboe@fusionio.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
---
kernel/trace/blktrace.c | 15 ++++-----------
1 files changed, 4 insertions(+), 11 deletions(-)
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index cbafed7..7aa40f8 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -703,28 +703,21 @@ void blk_trace_shutdown(struct request_queue *q)
*
**/
static void blk_add_trace_rq(struct request_queue *q, struct request *rq,
- u32 what)
+ u32 what)
{
struct blk_trace *bt = q->blk_trace;
- int rw = rq->cmd_flags & 0x03;

if (likely(!bt))
return;

- if (rq->cmd_flags & REQ_DISCARD)
- rw |= REQ_DISCARD;
-
- if (rq->cmd_flags & REQ_SECURE)
- rw |= REQ_SECURE;
-
if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
what |= BLK_TC_ACT(BLK_TC_PC);
- __blk_add_trace(bt, 0, blk_rq_bytes(rq), rw,
+ __blk_add_trace(bt, 0, blk_rq_bytes(rq), rq->cmd_flags,
what, rq->errors, rq->cmd_len, rq->cmd);
} else {
what |= BLK_TC_ACT(BLK_TC_FS);
- __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq), rw,
- what, rq->errors, 0, NULL);
+ __blk_add_trace(bt, blk_rq_pos(rq), blk_rq_bytes(rq),
+ rq->cmd_flags, what, rq->errors, 0, NULL);
}
}

--
1.6.3.GIT


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