diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/sys/zil.h | 1 | ||||
| -rw-r--r-- | include/sys/zil_impl.h | 39 | ||||
| -rw-r--r-- | include/sys/zio.h | 1 |
3 files changed, 33 insertions, 8 deletions
diff --git a/include/sys/zil.h b/include/sys/zil.h index 5513c7ce8..fc0cc5065 100644 --- a/include/sys/zil.h +++ b/include/sys/zil.h @@ -494,6 +494,7 @@ extern void zil_itx_destroy(itx_t *itx); extern void zil_itx_assign(zilog_t *zilog, itx_t *itx, dmu_tx_t *tx); extern void zil_commit(zilog_t *zilog, uint64_t oid); +extern void zil_commit_impl(zilog_t *zilog, uint64_t oid); extern int zil_vdev_offline(const char *osname, void *txarg); extern int zil_claim(struct dsl_pool *dp, diff --git a/include/sys/zil_impl.h b/include/sys/zil_impl.h index 7e27215ca..6901d51f0 100644 --- a/include/sys/zil_impl.h +++ b/include/sys/zil_impl.h @@ -36,13 +36,38 @@ extern "C" { #endif /* - * Possbile states for a given lwb structure. An lwb will start out in - * the "closed" state, and then transition to the "opened" state via a - * call to zil_lwb_write_open(). After the lwb is "open", it can - * transition into the "issued" state via zil_lwb_write_issue(). After - * the lwb's zio completes, and the vdev's are flushed, the lwb will - * transition into the "done" state via zil_lwb_write_done(), and the - * structure eventually freed. + * Possible states for a given lwb structure. + * + * An lwb will start out in the "closed" state, and then transition to + * the "opened" state via a call to zil_lwb_write_open(). When + * transitioning from "closed" to "opened" the zilog's "zl_issuer_lock" + * must be held. + * + * After the lwb is "opened", it can transition into the "issued" state + * via zil_lwb_write_issue(). Again, the zilog's "zl_issuer_lock" must + * be held when making this transition. + * + * After the lwb's zio completes, and the vdev's are flushed, the lwb + * will transition into the "done" state via zil_lwb_write_done(). When + * transitioning from "issued" to "done", the zilog's "zl_lock" must be + * held, *not* the "zl_issuer_lock". + * + * The zilog's "zl_issuer_lock" can become heavily contended in certain + * workloads, so we specifically avoid acquiring that lock when + * transitioning an lwb from "issued" to "done". This allows us to avoid + * having to acquire the "zl_issuer_lock" for each lwb ZIO completion, + * which would have added more lock contention on an already heavily + * contended lock. + * + * Additionally, correctness when reading an lwb's state is often + * achieved by exploiting the fact that these state transitions occur in + * this specific order; i.e. "closed" to "opened" to "issued" to "done". + * + * Thus, if an lwb is in the "closed" or "opened" state, holding the + * "zl_issuer_lock" will prevent a concurrent thread from transitioning + * that lwb to the "issued" state. Likewise, if an lwb is already in the + * "issued" state, holding the "zl_lock" will prevent a concurrent + * thread from transitioning that lwb to the "done" state. */ typedef enum { LWB_STATE_CLOSED, diff --git a/include/sys/zio.h b/include/sys/zio.h index 8beea7adf..bf4818e16 100644 --- a/include/sys/zio.h +++ b/include/sys/zio.h @@ -598,7 +598,6 @@ extern enum zio_checksum zio_checksum_dedup_select(spa_t *spa, extern enum zio_compress zio_compress_select(spa_t *spa, enum zio_compress child, enum zio_compress parent); -extern void zio_cancel(zio_t *zio); extern void zio_suspend(spa_t *spa, zio_t *zio); extern int zio_resume(spa_t *spa); extern void zio_resume_wait(spa_t *spa); |