Record skipped MMP writes in multihost_history

Once per pass through the MMP thread's loop, the vdev tree is walked to
find a suitable leaf to write the next MMP block to.  If no such leaf is
found, the thread sleeps for a while and resumes at the top of the loop.

Add an entry to multihost_history when no leaf can be found, and record
the reason in the error column.  The error code for such entries is a
bitfield, displayed in hex:

0x1  At least one vdev (interior or leaf) was not writeable.
0x2  At least one writeable leaf vdev was found, but it had a pending
MMP write.

timestamp = the time in seconds since the epoch when no leaf could be
found originally.

duration = the time (in ns) during which no MMP block was written for
this reason.  This does not include the preceeding inter-write period
nor the following inter-write period.

vdev_guid = the number of sequential cycles of the MMP thread looop when
this occurred.

Sample output, truncated to fit:

For records of skipped MMP writes the right-most column, vdev_path, is
reported as "-".

id   txg  timestamp   error  duration    mmp_delay  vdev_guid     ...
936  11   1520036441  0      146264      891422313  1740883117838 ...
937  11   1520036441  0      163956      888356657  7320395061548 ...
938  11   1520036442  0      130690      885314969  7320395061548 ...
939  11   1520036442  0      2001068577  882296582  1740883117838 ...
940  11   1520036443  0      161806      882296582  7320395061548 ...
941  11   1520036443  0x2    0           998020546  1             ...
942  11   1520036444  0      136585      998020546  7320395061548 ...
943  11   1520036444  0x2    0           998020257  1             ...
944  11   1520036445  5      2002662964  994160219  1740883117838 ...
945  11   1520036445  0x2    998073118   994160219  3             ...
946  11   1520036447  0      247136      994160219  7320395061548 ...

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
Closes #7212
This commit is contained in:
Olaf Faaland
2018-02-26 20:32:49 -05:00
committed by Brian Behlendorf
parent 14c240cede
commit d2160d0538
11 changed files with 263 additions and 50 deletions
+1
View File
@@ -43,6 +43,7 @@ typedef struct mmp_thread {
uberblock_t mmp_ub; /* last ub written by sync */
zio_t *mmp_zio_root; /* root of mmp write zios */
uint64_t mmp_kstat_id; /* unique id for next MMP write kstat */
int mmp_skip_error; /* reason for last skipped write */
} mmp_thread_t;
+4 -2
View File
@@ -887,10 +887,12 @@ extern txg_stat_t *spa_txg_history_init_io(spa_t *, uint64_t,
struct dsl_pool *);
extern void spa_txg_history_fini_io(spa_t *, txg_stat_t *);
extern void spa_tx_assign_add_nsecs(spa_t *spa, uint64_t nsecs);
extern int spa_mmp_history_set_skip(spa_t *spa, uint64_t mmp_kstat_id);
extern int spa_mmp_history_set(spa_t *spa, uint64_t mmp_kstat_id, int io_error,
hrtime_t duration);
extern void spa_mmp_history_add(uint64_t txg, uint64_t timestamp,
uint64_t mmp_delay, vdev_t *vd, int label, uint64_t mmp_kstat_id);
extern void *spa_mmp_history_add(spa_t *spa, uint64_t txg, uint64_t timestamp,
uint64_t mmp_delay, vdev_t *vd, int label, uint64_t mmp_kstat_id,
int error);
/* Pool configuration locks */
extern int spa_config_tryenter(spa_t *spa, int locks, void *tag, krw_t rw);