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Add additional state TXG_STATE_WAIT_FOR_SYNC for txg. 

In several cases when digging into kstats we can found two txgs
in SYNC state, e.g.

txg     birth            state  nreserved  nread      nwritten ...
985452  258127184872561  C      0          373948416  2376272384 ...
985453  258129016180616  C      0          378173440  28793344 ...
985454  258129016271523  S      0          0          0 ...
985455  258130864245986  S      0          0          0 ...
985456  258130867458851  O      0          0          0 ...

However only first txg (985454) is really syncing at this moment.
The other one (985455) marked as SYNCED is actually in a post-QUIESCED
state and waiting to start sync.   So, the new TXG_STATE_WAIT_FOR_SYNC
state between TXG_STATE_QUIESCED and TXG_STATE_SYNCED was added to
reveal this situation.

txg     birth            state  nreserved  nread      nwritten ...
1086896 235261068743969  C      0          163577856  8437248 ...
1086897 235262870830801  C      0          280625152  822594048 ...
1086898 235264172219064  S      0          0          0 ...
1086899 235264936134407  W      0          0          0 ...
1086900 235264936296156  O      0          0          0 ...

Signed-off-by: Igor Lvovsky <ilvovsky@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #2075
This commit is contained in:
Igor Lvovsky 2014-01-16 11:41:27 +02:00 committed by Brian Behlendorf
parent 93292b3081
commit 478d64fdae
3 changed files with 19 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/sys/spa.h
View File

@ -557,8 +557,9 @@ typedef enum txg_state {
TXG_STATE_BIRTH = 0,
TXG_STATE_OPEN = 1,
TXG_STATE_QUIESCED = 2,
TXG_STATE_SYNCED = 3,
TXG_STATE_COMMITTED = 4,
TXG_STATE_WAIT_FOR_SYNC = 3,
TXG_STATE_SYNCED = 4,
TXG_STATE_COMMITTED = 5,
} txg_state_t;
extern void spa_stats_init(spa_t *spa);

20
module/zfs/spa_stats.c
View File

@ -258,9 +258,9 @@ static int
spa_txg_history_headers(char *buf, size_t size)
{
size = snprintf(buf, size - 1, "%-8s %-16s %-5s %-12s %-12s %-12s "
"%-8s %-8s %-12s %-12s %-12s\n", "txg", "birth", "state",
"%-8s %-8s %-12s %-12s %-12s %-12s\n", "txg", "birth", "state",
"nreserved", "nread", "nwritten", "reads", "writes",
"otime", "qtime", "stime");
"otime", "qtime", "wtime", "stime");
buf[size] = '\0';
return (0);
@ -270,13 +270,14 @@ static int
spa_txg_history_data(char *buf, size_t size, void *data)
{
spa_txg_history_t *sth = (spa_txg_history_t *)data;
uint64_t open = 0, quiesce = 0, sync = 0;
uint64_t open = 0, quiesce = 0, wait = 0, sync = 0;
char state;
switch (sth->state) {
case TXG_STATE_BIRTH: state = 'B'; break;
case TXG_STATE_OPEN: state = 'O'; break;
case TXG_STATE_QUIESCED: state = 'Q'; break;
case TXG_STATE_WAIT_FOR_SYNC: state = 'W'; break;
case TXG_STATE_SYNCED: state = 'S'; break;
case TXG_STATE_COMMITTED: state = 'C'; break;
default: state = '?'; break;
@ -290,17 +291,22 @@ spa_txg_history_data(char *buf, size_t size, void *data)
quiesce = sth->times[TXG_STATE_QUIESCED] -
sth->times[TXG_STATE_OPEN];
if (sth->times[TXG_STATE_SYNCED])
sync = sth->times[TXG_STATE_SYNCED] -
if (sth->times[TXG_STATE_WAIT_FOR_SYNC])
wait = sth->times[TXG_STATE_WAIT_FOR_SYNC] -
sth->times[TXG_STATE_QUIESCED];
if (sth->times[TXG_STATE_SYNCED])
sync = sth->times[TXG_STATE_SYNCED] -
sth->times[TXG_STATE_WAIT_FOR_SYNC];
size = snprintf(buf, size - 1, "%-8llu %-16llu %-5c %-12llu "
"%-12llu %-12llu %-8llu %-8llu %-12llu %-12llu %-12llu\n",
"%-12llu %-12llu %-8llu %-8llu %-12llu %-12llu %-12llu %-12llu\n",
(longlong_t)sth->txg, sth->times[TXG_STATE_BIRTH], state,
(u_longlong_t)sth->nreserved,
(u_longlong_t)sth->nread, (u_longlong_t)sth->nwritten,
(u_longlong_t)sth->reads, (u_longlong_t)sth->writes,
(u_longlong_t)open, (u_longlong_t)quiesce, (u_longlong_t)sync);
(u_longlong_t)open, (u_longlong_t)quiesce, (u_longlong_t)wait,
(u_longlong_t)sync);
buf[size] = '\0';
return (0);

3
module/zfs/txg.c
View File

@ -555,6 +555,9 @@ txg_sync_thread(dsl_pool_t *dp)
txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
mutex_exit(&tx->tx_sync_lock);
spa_txg_history_set(spa, txg, TXG_STATE_WAIT_FOR_SYNC,
gethrtime());
start = ddi_get_lbolt();
spa_sync(spa, txg);
delta = ddi_get_lbolt() - start;