diff options
Diffstat (limited to 'sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg_impl.h')
| -rw-r--r-- | sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg_impl.h | 125 |
1 files changed, 125 insertions, 0 deletions
diff --git a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg_impl.h b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg_impl.h new file mode 100644 index 000000000000..bf3b269d707d --- /dev/null +++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/sys/txg_impl.h @@ -0,0 +1,125 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ + +/* + * Copyright 2009 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +/* + * Copyright (c) 2013, 2017 by Delphix. All rights reserved. + */ + +#ifndef _SYS_TXG_IMPL_H +#define _SYS_TXG_IMPL_H + +#include <sys/spa.h> +#include <sys/txg.h> + +#ifdef __cplusplus +extern "C" { +#endif + +/* + * The tx_cpu structure is a per-cpu structure that is used to track + * the number of active transaction holds (tc_count). As transactions + * are assigned into a transaction group the appropriate tc_count is + * incremented to indicate that there are pending changes that have yet + * to quiesce. Consumers evenutally call txg_rele_to_sync() to decrement + * the tc_count. A transaction group is not considered quiesced until all + * tx_cpu structures have reached a tc_count of zero. + * + * This structure is a per-cpu structure by design. Updates to this structure + * are frequent and concurrent. Having a single structure would result in + * heavy lock contention so a per-cpu design was implemented. With the fanned + * out mutex design, consumers only need to lock the mutex associated with + * thread's cpu. + * + * The tx_cpu contains two locks, the tc_lock and tc_open_lock. + * The tc_lock is used to protect all members of the tx_cpu structure with + * the exception of the tc_open_lock. This lock should only be held for a + * short period of time, typically when updating the value of tc_count. + * + * The tc_open_lock protects the tx_open_txg member of the tx_state structure. + * This lock is used to ensure that transactions are only assigned into + * the current open transaction group. In order to move the current open + * transaction group to the quiesce phase, the txg_quiesce thread must + * grab all tc_open_locks, increment the tx_open_txg, and drop the locks. + * The tc_open_lock is held until the transaction is assigned into the + * transaction group. Typically, this is a short operation but if throttling + * is occuring it may be held for longer periods of time. + */ +struct tx_cpu { + kmutex_t tc_open_lock; /* protects tx_open_txg */ + kmutex_t tc_lock; /* protects the rest of this struct */ + kcondvar_t tc_cv[TXG_SIZE]; + uint64_t tc_count[TXG_SIZE]; /* tx hold count on each txg */ + list_t tc_callbacks[TXG_SIZE]; /* commit cb list */ + char tc_pad[8]; /* pad to fill 3 cache lines */ +}; + +/* + * The tx_state structure maintains the state information about the different + * stages of the pool's transcation groups. A per pool tx_state structure + * is used to track this information. The tx_state structure also points to + * an array of tx_cpu structures (described above). Although the tx_sync_lock + * is used to protect the members of this structure, it is not used to + * protect the tx_open_txg. Instead a special lock in the tx_cpu structure + * is used. Readers of tx_open_txg must grab the per-cpu tc_open_lock. + * Any thread wishing to update tx_open_txg must grab the tc_open_lock on + * every cpu (see txg_quiesce()). + */ +typedef struct tx_state { + tx_cpu_t *tx_cpu; /* protects access to tx_open_txg */ + kmutex_t tx_sync_lock; /* protects the rest of this struct */ + + uint64_t tx_open_txg; /* currently open txg id */ + uint64_t tx_quiescing_txg; /* currently quiescing txg id */ + uint64_t tx_quiesced_txg; /* quiesced txg waiting for sync */ + uint64_t tx_syncing_txg; /* currently syncing txg id */ + uint64_t tx_synced_txg; /* last synced txg id */ + + hrtime_t tx_open_time; /* start time of tx_open_txg */ + + uint64_t tx_sync_txg_waiting; /* txg we're waiting to sync */ + uint64_t tx_quiesce_txg_waiting; /* txg we're waiting to open */ + + kcondvar_t tx_sync_more_cv; + kcondvar_t tx_sync_done_cv; + kcondvar_t tx_quiesce_more_cv; + kcondvar_t tx_quiesce_done_cv; + kcondvar_t tx_timeout_cv; + kcondvar_t tx_exit_cv; /* wait for all threads to exit */ + + uint8_t tx_threads; /* number of threads */ + uint8_t tx_exiting; /* set when we're exiting */ + + kthread_t *tx_sync_thread; + kthread_t *tx_quiesce_thread; + + taskq_t *tx_commit_cb_taskq; /* commit callback taskq */ +} tx_state_t; + +#ifdef __cplusplus +} +#endif + +#endif /* _SYS_TXG_IMPL_H */ |