/* * 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 */
