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MMP delay logic changes #7068

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MMP delay logic changes #7068

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891b2e7
MMP: increase delay for busy pool before suspending
Jan 16, 2018
abd17be
MMP: base mmp_fail_interval on mmp_import_interval
Jan 16, 2018
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1 change: 0 additions & 1 deletion include/sys/mmp.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,6 @@ extern "C" {
#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 */
Expand Down
60 changes: 41 additions & 19 deletions module/zfs/mmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -115,14 +115,13 @@ uint_t zfs_multihost_import_intervals = MMP_DEFAULT_IMPORT_INTERVALS;
* configuration may take action such as suspending the pool or taking a
* device offline.
*
* When zfs_multihost_fail_intervals > 0 then sequential mmp write failures will
* cause the pool to be suspended. This occurs when
* When zfs_multihost_fail_intervals > 0 then sequential mmp write failures
* will cause the pool to be suspended. This occurs when
* zfs_multihost_fail_intervals * zfs_multihost_interval milliseconds have
* passed since the last successful mmp write. This guarantees the activity
* test will see mmp writes if the
* pool is imported.
* test will see mmp writes if the pool is imported.
*/
uint_t zfs_multihost_fail_intervals = MMP_DEFAULT_FAIL_INTERVALS;
uint_t zfs_multihost_fail_intervals = MMP_DEFAULT_IMPORT_INTERVALS / 2;

static void mmp_thread(void *arg);

Expand Down Expand Up @@ -249,7 +248,7 @@ mmp_write_done(zio_t *zio)
goto unlock;

/*
* Mmp writes are queued on a fixed schedule, but under many
* MMP writes are queued on a fixed schedule, but under many
* circumstances, such as a busy device or faulty hardware,
* the writes will complete at variable, much longer,
* intervals. In these cases, another node checking for
Expand All @@ -269,8 +268,7 @@ mmp_write_done(zio_t *zio)
if (delay > mts->mmp_delay)
mts->mmp_delay = delay;
else
mts->mmp_delay = (delay + mts->mmp_delay * 127) /
128;
mts->mmp_delay = (delay + mts->mmp_delay * 127) / 128;
} else {
mts->mmp_delay = 0;
}
Expand Down Expand Up @@ -381,16 +379,40 @@ mmp_thread(void *arg)
uint64_t mmp_fail_intervals = zfs_multihost_fail_intervals;
uint64_t mmp_interval = MSEC2NSEC(
MAX(zfs_multihost_interval, MMP_MIN_INTERVAL));
uint64_t fail_interval;
int vdev_leaves = MAX(vdev_count_leaves(spa), 1);
boolean_t suspended = spa_suspended(spa);
boolean_t multihost = spa_multihost(spa);
hrtime_t start, next_time;

start = gethrtime();
if (multihost) {
next_time = start + mmp_interval /
MAX(vdev_count_leaves(spa), 1);
} else {
if (multihost)
next_time = start + mmp_interval / vdev_leaves;
else
next_time = start + MSEC2NSEC(MMP_DEFAULT_INTERVAL);

/*
* Don't allow fail_intervals larger than import_intervals,
* as this could allow an active pool to be imported on a peer.
*
* We don't actually know what the import_interval is on the
* peer node, but the best assumption is that it is configured
* in the same way as the local node.
*/
if (mmp_fail_intervals >= zfs_multihost_import_intervals) {
static boolean_t warned = B_FALSE;

if (!warned) {
cmn_err(CE_WARN,
"zfs_multihost_fail_intervals %u >= "
"zfs_multihost_import_interval %u, "
"using smaller value",
zfs_multihost_fail_intervals,
zfs_multihost_import_interval);
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zfs_multihost_import_interval -> zfs_multihost_import_intervals ?

warned = B_TRUE;
}

mmp_fail_intervals = zfs_multihost_import_intervals - 1;
}

/*
Expand All @@ -417,16 +439,16 @@ mmp_thread(void *arg)
* immediately suspended before writes can occur at the new
* higher frequency.
*/
if ((mmp_interval * mmp_fail_intervals) < max_fail_ns) {
max_fail_ns = ((31 * max_fail_ns) + (mmp_interval *
mmp_fail_intervals)) / 32;
} else {
max_fail_ns = mmp_interval * mmp_fail_intervals;
}
fail_interval = MAX(mmp_interval,
mmp->mmp_delay * vdev_leaves) * mmp_fail_intervals;
if (fail_interval < max_fail_ns)
max_fail_ns = ((31 * max_fail_ns) + fail_interval) / 32;
else
max_fail_ns = fail_interval;

/*
* Suspend the pool if no MMP write has succeeded in over
* mmp_interval * mmp_fail_intervals nanoseconds.
* mmp_delay * vdev_leaves * mmp_fail_intervals nanoseconds.
*/
if (!suspended && mmp_fail_intervals && multihost &&
(start - mmp->mmp_last_write) > max_fail_ns) {
Expand Down