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srcu: Move ->level from srcu_struct to srcu_usage

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This commit moves the ->level[] array from the srcu_struct structure to
the srcu_usage structure to reduce the size of the former in order to
improve cache locality.

Suggested-by: Christoph Hellwig <hch@lst.de>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: "Zhang, Qiang1" <qiang1.zhang@intel.com>
Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2023-03-17 14:43:08 -07:00
parent 95433f7263
commit 208f41b131
2 changed files with 9 additions and 9 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
include/linux/srcutree.h
View file

@ -62,14 +62,14 @@ struct srcu_node {
*/
struct srcu_usage {
struct srcu_node *node; /* Combining tree. */
struct srcu_node *level[RCU_NUM_LVLS + 1];
/* First node at each level. */
};
/*
* Per-SRCU-domain structure, similar in function to rcu_state.
*/
struct srcu_struct {
struct srcu_node *level[RCU_NUM_LVLS + 1];
/* First node at each level. */
int srcu_size_state; /* Small-to-big transition state. */
struct mutex srcu_cb_mutex; /* Serialize CB preparation. */
spinlock_t __private lock; /* Protect counters and size state. */

14
kernel/rcu/srcutree.c
View file

@ -178,9 +178,9 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags)
return false;
/* Work out the overall tree geometry. */
ssp->level[0] = &ssp->srcu_sup->node[0];
ssp->srcu_sup->level[0] = &ssp->srcu_sup->node[0];
for (i = 1; i < rcu_num_lvls; i++)
ssp->level[i] = ssp->level[i - 1] + num_rcu_lvl[i - 1];
ssp->srcu_sup->level[i] = ssp->srcu_sup->level[i - 1] + num_rcu_lvl[i - 1];
rcu_init_levelspread(levelspread, num_rcu_lvl);
/* Each pass through this loop initializes one srcu_node structure. */
@ -202,10 +202,10 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags)
}
/* Non-root node. */
if (snp == ssp->level[level + 1])
if (snp == ssp->srcu_sup->level[level + 1])
level++;
snp->srcu_parent = ssp->level[level - 1] +
(snp - ssp->level[level]) /
snp->srcu_parent = ssp->srcu_sup->level[level - 1] +
(snp - ssp->srcu_sup->level[level]) /
levelspread[level - 1];
}
@ -214,7 +214,7 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags)
* leaves of the srcu_node tree.
*/
level = rcu_num_lvls - 1;
snp_first = ssp->level[level];
snp_first = ssp->srcu_sup->level[level];
for_each_possible_cpu(cpu) {
sdp = per_cpu_ptr(ssp->sda, cpu);
sdp->mynode = &snp_first[cpu / levelspread[level]];
@ -889,7 +889,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
srcu_for_each_node_breadth_first(ssp, snp) {
spin_lock_irq_rcu_node(snp);
cbs = false;
last_lvl = snp >= ssp->level[rcu_num_lvls - 1];
last_lvl = snp >= ssp->srcu_sup->level[rcu_num_lvls - 1];
if (last_lvl)
cbs = ss_state < SRCU_SIZE_BIG || snp->srcu_have_cbs[idx] == gpseq;
snp->srcu_have_cbs[idx] = gpseq;