iowatcher: Only hash IOs if there are completion or issue events

We use an IO hash table to keep track of the IOs in flight, and this is
used to calculate the latencies from when we issue the IO to when
we complete the IO.

But if there are no completion events, io is never removed from the hash
table.  It grows very large and slows down the run.

Since we already scan all the events looking for outliers, this commit
checks for each major type of event during the scan.  If there are
no completion and no issue events, we don't bother inserting things
into the hash table.

If there are no completion events, we clean up during the issue event.

Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 37 insertions, 27 deletions

diff --git a/iowatcher/blkparse.c b/iowatcher/blkparse.c
index 7d32f40..84c26e1 100644
--- a/iowatcher/blkparse.c
+++ b/iowatcher/blkparse.c
@@ -264,17 +264,15 @@ static int hash_queued_io(struct blk_io_trace *io)
 	return 0;
 }
 
-static int hash_dispatched_io(struct blk_io_trace *io)
+static struct pending_io *hash_dispatched_io(struct blk_io_trace *io)
 {
 	struct pending_io *pio;
 
 	pio = io_hash_table_search(io->sector);
-	if (!pio) {
-		/* crud, the IO isn't here */
-		return -EEXIST;
-	}
+	if (!pio)
+		hash_queued_io(io);
 	pio->dispatch_time = io->time;
-	return 0;
+	return pio;
 }
 
 static struct pending_io *hash_completed_io(struct blk_io_trace *io)
@@ -551,6 +549,27 @@ void find_extreme_offsets(struct trace *trace, u64 *min_ret, u64 *max_ret, u64 *
 	*max_offset_ret = max_bank_offset;
 }
 
+static void check_io_types(struct trace *trace)
+{
+	struct blk_io_trace *io = trace->io;
+	int action = io->action & BLK_TA_MASK;
+
+	if (!(io->action & BLK_TC_ACT(BLK_TC_NOTIFY))) {
+		switch (action) {
+		case __BLK_TA_COMPLETE:
+			trace->found_completion = 1;
+			break;
+		case __BLK_TA_ISSUE:
+			trace->found_issue = 1;
+			break;
+		case __BLK_TA_QUEUE:
+			trace->found_queue = 1;
+			break;
+		};
+	}
+}
+
+
 int filter_outliers(struct trace *trace, u64 min_offset, u64 max_offset,
 		    u64 *yzoom_min, u64 *yzoom_max)
 {
@@ -566,6 +585,7 @@ int filter_outliers(struct trace *trace, u64 min_offset, u64 max_offset,
 	memset(min_per_bucket, 0xff, sizeof(u64) * 11);
 	first_record(trace);
 	while (1) {
+		check_io_types(trace);
 		if (!(trace->io->action & BLK_TC_ACT(BLK_TC_NOTIFY)) &&
 		    (trace->io->action & BLK_TA_MASK) == __BLK_TA_QUEUE) {
 			u64 off = (trace->io->sector << 9) - min_offset;
@@ -575,7 +595,7 @@ int filter_outliers(struct trace *trace, u64 min_offset, u64 max_offset,
 			if (off < min_per_bucket[slot])
 				min_per_bucket[slot] = off;
 
- 			off += trace->io->bytes;
+			off += trace->io->bytes;
 			slot = (int)(off / bytes_per_bucket);
 			hits[slot]++;
 			if (off > max_per_bucket[slot])
@@ -834,17 +854,18 @@ void add_io(struct trace *trace, struct trace_file *tf)
 
 void add_pending_io(struct trace *trace, struct graph_line_data *gld)
 {
-	int ret;
 	int seconds;
 	struct blk_io_trace *io = trace->io;
 	int action = io->action & BLK_TA_MASK;
 	double avg;
+	struct pending_io *pio;
 
 	if (io->action & BLK_TC_ACT(BLK_TC_NOTIFY))
 		return;
 
 	if (action == __BLK_TA_QUEUE) {
-		hash_queued_io(trace->io);
+		if (trace->found_issue || trace->found_completion)
+			hash_queued_io(trace->io);
 		return;
 	}
 	if (action != __BLK_TA_ISSUE)
@@ -854,10 +875,15 @@ void add_pending_io(struct trace *trace, struct graph_line_data *gld)
 	if (seconds > gld->max_seconds)
 		return;
 
-	ret = hash_dispatched_io(trace->io);
-	if (ret)
+	pio = hash_dispatched_io(trace->io);
+	if (!pio)
 		return;
 
+	if (!trace->found_completion) {
+		list_del(&pio->hash_list);
+		free(pio);
+	}
+
 	ios_in_flight++;
 
 	gld->data[seconds].sum += ios_in_flight;
@@ -934,21 +960,5 @@ void add_iop(struct trace *trace, struct graph_line_data *gld)
 
 void check_record(struct trace *trace)
 {
-	struct blk_io_trace *io = trace->io;
-	int action = io->action & BLK_TA_MASK;
-
-	if (!(io->action & BLK_TC_ACT(BLK_TC_NOTIFY))) {
-		switch (action) {
-		case __BLK_TA_COMPLETE:
-			trace->found_completion = 1;
-			break;
-		case __BLK_TA_ISSUE:
-			trace->found_issue = 1;
-			break;
-		case __BLK_TA_QUEUE:
-			trace->found_queue = 1;
-			break;
-		};
-	}
 	handle_notify(trace);
 }