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Fix txg_wait_open() load average inflation

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Callers of txg_wait_open() which set should_quiesce=B_TRUE should be
accounted for as iowait time.  Otherwise, the caller is understood
to be idle and cv_wait_sig() is used to prevent incorrectly inflating
the system load average.

Similarly txg_wait_wait() has been updated to use cv_wait_io() to
be accounted against iowait.

Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: Olaf Faaland <faaland1@llnl.gov>
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #8550
Closes #8558
This commit is contained in:
Brian Behlendorf 2019-04-04 09:44:46 -07:00 committed by GitHub
parent ce4432c542
commit f4e35b165c
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 25 additions and 5 deletions
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24
module/zfs/txg.c
View File

@ -242,11 +242,17 @@ txg_thread_wait(tx_state_t *tx, callb_cpr_t *cpr, kcondvar_t *cv, clock_t time)
{
CALLB_CPR_SAFE_BEGIN(cpr);
if (time)
/*
* cv_wait_sig() is used instead of cv_wait() in order to prevent
* this process from incorrectly contributing to the system load
* average when idle.
*/
if (time) {
(void) cv_timedwait_sig(cv, &tx->tx_sync_lock,
ddi_get_lbolt() + time);
else
} else {
cv_wait_sig(cv, &tx->tx_sync_lock);
}
CALLB_CPR_SAFE_END(cpr, &tx->tx_sync_lock);
}
@ -689,7 +695,7 @@ txg_wait_synced(dsl_pool_t *dp, uint64_t txg)
"tx_synced=%llu waiting=%llu dp=%p\n",
tx->tx_synced_txg, tx->tx_sync_txg_waiting, dp);
cv_broadcast(&tx->tx_sync_more_cv);
cv_wait(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
cv_wait_io(&tx->tx_sync_done_cv, &tx->tx_sync_lock);
}
mutex_exit(&tx->tx_sync_lock);
}
@ -715,7 +721,17 @@ txg_wait_open(dsl_pool_t *dp, uint64_t txg, boolean_t should_quiesce)
txg, tx->tx_quiesce_txg_waiting, tx->tx_sync_txg_waiting);
while (tx->tx_open_txg < txg) {
cv_broadcast(&tx->tx_quiesce_more_cv);
cv_wait(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
/*
* Callers setting should_quiesce will use cv_wait_io() and
* be accounted for as iowait time. Otherwise, the caller is
* understood to be idle and cv_wait_sig() is used to prevent
* incorrectly inflating the system load average.
*/
if (should_quiesce == B_TRUE) {
cv_wait_io(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
} else {
cv_wait_sig(&tx->tx_quiesce_done_cv, &tx->tx_sync_lock);
}
}
mutex_exit(&tx->tx_sync_lock);
}

6
module/zfs/zthr.c
View File

@ -234,7 +234,11 @@ zthr_procedure(void *arg)
t->zthr_func(t->zthr_arg, t);
mutex_enter(&t->zthr_state_lock);
} else {
/* go to sleep */
/*
* cv_wait_sig() is used instead of cv_wait() in
* order to prevent this process from incorrectly
* contributing to the system load average when idle.
*/
if (t->zthr_wait_time == 0) {
cv_wait_sig(&t->zthr_cv, &t->zthr_state_lock);
} else {