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block: latency accounting

Account the total latency for read/write/flush requests.  This allows
management tools to average it based on a snapshot of the nr ops
counters and allow checking for SLAs or provide statistics.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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1 parent a597e79 commit c488c7f649106d09df76f697adccbe6e72520b26 Christoph Hellwig committed with Kevin Wolf Aug 25, 2011
Showing with 38 additions and 3 deletions.
  1. +17 −3 block.c
  2. +1 −0 block.h
  3. +2 −0 block_int.h
  4. +18 −0 qmp-commands.hx
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20 block.c
@@ -1916,12 +1916,18 @@ static void bdrv_stats_iter(QObject *data, void *opaque)
" rd_operations=%" PRId64
" wr_operations=%" PRId64
" flush_operations=%" PRId64
+ " wr_total_time_ns=%" PRId64
+ " rd_total_time_ns=%" PRId64
+ " flush_total_time_ns=%" PRId64
"\n",
qdict_get_int(qdict, "rd_bytes"),
qdict_get_int(qdict, "wr_bytes"),
qdict_get_int(qdict, "rd_operations"),
qdict_get_int(qdict, "wr_operations"),
- qdict_get_int(qdict, "flush_operations"));
+ qdict_get_int(qdict, "flush_operations"),
+ qdict_get_int(qdict, "wr_total_time_ns"),
+ qdict_get_int(qdict, "rd_total_time_ns"),
+ qdict_get_int(qdict, "flush_total_time_ns"));
}
void bdrv_stats_print(Monitor *mon, const QObject *data)
@@ -1940,15 +1946,21 @@ static QObject* bdrv_info_stats_bs(BlockDriverState *bs)
"'rd_operations': %" PRId64 ","
"'wr_operations': %" PRId64 ","
"'wr_highest_offset': %" PRId64 ","
- "'flush_operations': %" PRId64
+ "'flush_operations': %" PRId64 ","
+ "'wr_total_time_ns': %" PRId64 ","
+ "'rd_total_time_ns': %" PRId64 ","
+ "'flush_total_time_ns': %" PRId64
"} }",
bs->nr_bytes[BDRV_ACCT_READ],
bs->nr_bytes[BDRV_ACCT_WRITE],
bs->nr_ops[BDRV_ACCT_READ],
bs->nr_ops[BDRV_ACCT_WRITE],
bs->wr_highest_sector *
(uint64_t)BDRV_SECTOR_SIZE,
- bs->nr_ops[BDRV_ACCT_FLUSH]);
+ bs->nr_ops[BDRV_ACCT_FLUSH],
+ bs->total_time_ns[BDRV_ACCT_WRITE],
+ bs->total_time_ns[BDRV_ACCT_READ],
+ bs->total_time_ns[BDRV_ACCT_FLUSH]);
dict = qobject_to_qdict(res);
if (*bs->device_name) {
@@ -3160,6 +3172,7 @@ bdrv_acct_start(BlockDriverState *bs, BlockAcctCookie *cookie, int64_t bytes,
assert(type < BDRV_MAX_IOTYPE);
cookie->bytes = bytes;
+ cookie->start_time_ns = get_clock();
cookie->type = type;
}
@@ -3170,6 +3183,7 @@ bdrv_acct_done(BlockDriverState *bs, BlockAcctCookie *cookie)
bs->nr_bytes[cookie->type] += cookie->bytes;
bs->nr_ops[cookie->type]++;
+ bs->total_time_ns[cookie->type] += get_clock() - cookie->start_time_ns;
}
int bdrv_img_create(const char *filename, const char *fmt,
View
@@ -264,6 +264,7 @@ enum BlockAcctType {
typedef struct BlockAcctCookie {
int64_t bytes;
+ int64_t start_time_ns;
enum BlockAcctType type;
} BlockAcctCookie;
View
@@ -28,6 +28,7 @@
#include "qemu-option.h"
#include "qemu-queue.h"
#include "qemu-coroutine.h"
+#include "qemu-timer.h"
#define BLOCK_FLAG_ENCRYPT 1
#define BLOCK_FLAG_COMPAT6 4
@@ -186,6 +187,7 @@ struct BlockDriverState {
/* I/O stats (display with "info blockstats"). */
uint64_t nr_bytes[BDRV_MAX_IOTYPE];
uint64_t nr_ops[BDRV_MAX_IOTYPE];
+ uint64_t total_time_ns[BDRV_MAX_IOTYPE];
uint64_t wr_highest_sector;
/* Whether the disk can expand beyond total_sectors */
View
@@ -1202,6 +1202,9 @@ Each json-object contain the following:
- "rd_operations": read operations (json-int)
- "wr_operations": write operations (json-int)
- "flush_operations": cache flush operations (json-int)
+ - "wr_total_time_ns": total time spend on writes in nano-seconds (json-int)
+ - "rd_total_time_ns": total time spend on reads in nano-seconds (json-int)
+ - "flush_total_time_ns": total time spend on cache flushes in nano-seconds (json-int)
- "wr_highest_offset": Highest offset of a sector written since the
BlockDriverState has been opened (json-int)
- "parent": Contains recursively the statistics of the underlying
@@ -1223,6 +1226,9 @@ Example:
"wr_operations":751,
"rd_bytes":122567168,
"rd_operations":36772
+ "wr_total_times_ns":313253456
+ "rd_total_times_ns":3465673657
+ "flush_total_times_ns":49653
"flush_operations":61,
}
},
@@ -1233,6 +1239,9 @@ Example:
"rd_bytes":122739200,
"rd_operations":36604
"flush_operations":51,
+ "wr_total_times_ns":313253456
+ "rd_total_times_ns":3465673657
+ "flush_total_times_ns":49653
}
},
{
@@ -1244,6 +1253,9 @@ Example:
"rd_bytes":0,
"rd_operations":0
"flush_operations":0,
+ "wr_total_times_ns":0
+ "rd_total_times_ns":0
+ "flush_total_times_ns":0
}
},
{
@@ -1255,6 +1267,9 @@ Example:
"rd_bytes":0,
"rd_operations":0
"flush_operations":0,
+ "wr_total_times_ns":0
+ "rd_total_times_ns":0
+ "flush_total_times_ns":0
}
},
{
@@ -1266,6 +1281,9 @@ Example:
"rd_bytes":0,
"rd_operations":0
"flush_operations":0,
+ "wr_total_times_ns":0
+ "rd_total_times_ns":0
+ "flush_total_times_ns":0
}
}
]

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