freebsd-dev/include/sys/mmp.h
Olaf Faaland d2160d0538 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
2018-03-06 15:15:15 -08:00

67 lines
1.9 KiB
C

/*
* CDDL HEADER START
*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*
* CDDL HEADER END
*/
/*
* Copyright (C) 2017 by Lawrence Livermore National Security, LLC.
*/
#ifndef _SYS_MMP_H
#define _SYS_MMP_H
#include <sys/spa.h>
#include <sys/zfs_context.h>
#include <sys/uberblock_impl.h>
#ifdef __cplusplus
extern "C" {
#endif
#define MMP_MIN_INTERVAL 100 /* ms */
#define MMP_DEFAULT_INTERVAL 1000 /* ms */
#define MMP_DEFAULT_IMPORT_INTERVALS 10
#define MMP_DEFAULT_FAIL_INTERVALS 5
typedef struct mmp_thread {
kmutex_t mmp_thread_lock; /* protect thread mgmt fields */
kcondvar_t mmp_thread_cv;
kthread_t *mmp_thread;
uint8_t mmp_thread_exiting;
kmutex_t mmp_io_lock; /* protect below */
hrtime_t mmp_last_write; /* last successful MMP write */
uint64_t mmp_delay; /* decaying avg ns between MMP writes */
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;
extern void mmp_init(struct spa *spa);
extern void mmp_fini(struct spa *spa);
extern void mmp_thread_start(struct spa *spa);
extern void mmp_thread_stop(struct spa *spa);
extern void mmp_update_uberblock(struct spa *spa, struct uberblock *ub);
extern void mmp_signal_all_threads(void);
/* Global tuning */
extern ulong_t zfs_multihost_interval;
extern uint_t zfs_multihost_fail_intervals;
extern uint_t zfs_multihost_import_intervals;
#ifdef __cplusplus
}
#endif
#endif /* _SYS_MMP_H */