mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-30 13:56:53 +07:00
aaaad0bfac
The rcu_node_tree.h and rcu_segcblist.h header files in the include/linux directory might appear at first sight to be internal to the RCU implementation. However, the definitions in these files are needed to determine the size of TREE SRCU's srcu_struct structure, so they must be externally visible, which is why they live in include/linux. This commit adds comments to this effect to those files. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
104 lines
4.3 KiB
C
104 lines
4.3 KiB
C
/*
|
|
* RCU node combining tree definitions. These are used to compute
|
|
* global attributes while avoiding common-case global contention. A key
|
|
* property that these computations rely on is a tournament-style approach
|
|
* where only one of the tasks contending a lower level in the tree need
|
|
* advance to the next higher level. If properly configured, this allows
|
|
* unlimited scalability while maintaining a constant level of contention
|
|
* on the root node.
|
|
*
|
|
* This seemingly RCU-private file must be available to SRCU users
|
|
* because the size of the TREE SRCU srcu_struct structure depends
|
|
* on these definitions.
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, you can access it online at
|
|
* http://www.gnu.org/licenses/gpl-2.0.html.
|
|
*
|
|
* Copyright IBM Corporation, 2017
|
|
*
|
|
* Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
|
|
*/
|
|
|
|
#ifndef __LINUX_RCU_NODE_TREE_H
|
|
#define __LINUX_RCU_NODE_TREE_H
|
|
|
|
/*
|
|
* Define shape of hierarchy based on NR_CPUS, CONFIG_RCU_FANOUT, and
|
|
* CONFIG_RCU_FANOUT_LEAF.
|
|
* In theory, it should be possible to add more levels straightforwardly.
|
|
* In practice, this did work well going from three levels to four.
|
|
* Of course, your mileage may vary.
|
|
*/
|
|
|
|
#ifdef CONFIG_RCU_FANOUT
|
|
#define RCU_FANOUT CONFIG_RCU_FANOUT
|
|
#else /* #ifdef CONFIG_RCU_FANOUT */
|
|
# ifdef CONFIG_64BIT
|
|
# define RCU_FANOUT 64
|
|
# else
|
|
# define RCU_FANOUT 32
|
|
# endif
|
|
#endif /* #else #ifdef CONFIG_RCU_FANOUT */
|
|
|
|
#ifdef CONFIG_RCU_FANOUT_LEAF
|
|
#define RCU_FANOUT_LEAF CONFIG_RCU_FANOUT_LEAF
|
|
#else /* #ifdef CONFIG_RCU_FANOUT_LEAF */
|
|
#define RCU_FANOUT_LEAF 16
|
|
#endif /* #else #ifdef CONFIG_RCU_FANOUT_LEAF */
|
|
|
|
#define RCU_FANOUT_1 (RCU_FANOUT_LEAF)
|
|
#define RCU_FANOUT_2 (RCU_FANOUT_1 * RCU_FANOUT)
|
|
#define RCU_FANOUT_3 (RCU_FANOUT_2 * RCU_FANOUT)
|
|
#define RCU_FANOUT_4 (RCU_FANOUT_3 * RCU_FANOUT)
|
|
|
|
#if NR_CPUS <= RCU_FANOUT_1
|
|
# define RCU_NUM_LVLS 1
|
|
# define NUM_RCU_LVL_0 1
|
|
# define NUM_RCU_NODES NUM_RCU_LVL_0
|
|
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0 }
|
|
# define RCU_NODE_NAME_INIT { "rcu_node_0" }
|
|
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0" }
|
|
#elif NR_CPUS <= RCU_FANOUT_2
|
|
# define RCU_NUM_LVLS 2
|
|
# define NUM_RCU_LVL_0 1
|
|
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
|
|
# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1)
|
|
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1 }
|
|
# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1" }
|
|
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1" }
|
|
#elif NR_CPUS <= RCU_FANOUT_3
|
|
# define RCU_NUM_LVLS 3
|
|
# define NUM_RCU_LVL_0 1
|
|
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
|
|
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
|
|
# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2)
|
|
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2 }
|
|
# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2" }
|
|
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2" }
|
|
#elif NR_CPUS <= RCU_FANOUT_4
|
|
# define RCU_NUM_LVLS 4
|
|
# define NUM_RCU_LVL_0 1
|
|
# define NUM_RCU_LVL_1 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_3)
|
|
# define NUM_RCU_LVL_2 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_2)
|
|
# define NUM_RCU_LVL_3 DIV_ROUND_UP(NR_CPUS, RCU_FANOUT_1)
|
|
# define NUM_RCU_NODES (NUM_RCU_LVL_0 + NUM_RCU_LVL_1 + NUM_RCU_LVL_2 + NUM_RCU_LVL_3)
|
|
# define NUM_RCU_LVL_INIT { NUM_RCU_LVL_0, NUM_RCU_LVL_1, NUM_RCU_LVL_2, NUM_RCU_LVL_3 }
|
|
# define RCU_NODE_NAME_INIT { "rcu_node_0", "rcu_node_1", "rcu_node_2", "rcu_node_3" }
|
|
# define RCU_FQS_NAME_INIT { "rcu_node_fqs_0", "rcu_node_fqs_1", "rcu_node_fqs_2", "rcu_node_fqs_3" }
|
|
#else
|
|
# error "CONFIG_RCU_FANOUT insufficient for NR_CPUS"
|
|
#endif /* #if (NR_CPUS) <= RCU_FANOUT_1 */
|
|
|
|
#endif /* __LINUX_RCU_NODE_TREE_H */
|