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srcu: Move ->srcu_gp_mutex from srcu_struct to srcu_usage 

This commit moves the ->srcu_gp_mutex field 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 19:13:16 -07:00
parent b3fb11f7e9
commit e3a6ab25cf
2 changed files with 8 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/srcutree.h
View File

@ -67,13 +67,13 @@ struct srcu_usage {
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. */
struct mutex srcu_gp_mutex; /* Serialize GP work. */
};
/*
* Per-SRCU-domain structure, similar in function to rcu_state.
*/
struct srcu_struct {
struct mutex srcu_gp_mutex; /* Serialize GP work. */
unsigned int srcu_idx; /* Current rdr array element. */
unsigned long srcu_gp_seq; /* Grace-period seq #. */
unsigned long srcu_gp_seq_needed; /* Latest gp_seq needed. */

14
kernel/rcu/srcutree.c
View File

@ -245,7 +245,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
ssp->srcu_sup->node = NULL;
mutex_init(&ssp->srcu_sup->srcu_cb_mutex);
mutex_init(&ssp->srcu_gp_mutex);
mutex_init(&ssp->srcu_sup->srcu_gp_mutex);
ssp->srcu_idx = 0;
ssp->srcu_gp_seq = 0;
ssp->srcu_barrier_seq = 0;
@ -876,7 +876,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
if (ULONG_CMP_LT(ssp->srcu_gp_seq_needed_exp, gpseq))
WRITE_ONCE(ssp->srcu_gp_seq_needed_exp, gpseq);
spin_unlock_irq_rcu_node(ssp->srcu_sup);
mutex_unlock(&ssp->srcu_gp_mutex);
mutex_unlock(&ssp->srcu_sup->srcu_gp_mutex);
/* A new grace period can start at this point. But only one. */
/* Initiate callback invocation as needed. */
@ -1585,7 +1585,7 @@ static void srcu_advance_state(struct srcu_struct *ssp)
{
int idx;
mutex_lock(&ssp->srcu_gp_mutex);
mutex_lock(&ssp->srcu_sup->srcu_gp_mutex);
/*
* Because readers might be delayed for an extended period after
@ -1603,7 +1603,7 @@ static void srcu_advance_state(struct srcu_struct *ssp)
if (ULONG_CMP_GE(ssp->srcu_gp_seq, ssp->srcu_gp_seq_needed)) {
WARN_ON_ONCE(rcu_seq_state(ssp->srcu_gp_seq));
spin_unlock_irq_rcu_node(ssp->srcu_sup);
mutex_unlock(&ssp->srcu_gp_mutex);
mutex_unlock(&ssp->srcu_sup->srcu_gp_mutex);
return;
}
idx = rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq));
@ -1611,7 +1611,7 @@ static void srcu_advance_state(struct srcu_struct *ssp)
srcu_gp_start(ssp);
spin_unlock_irq_rcu_node(ssp->srcu_sup);
if (idx != SRCU_STATE_IDLE) {
mutex_unlock(&ssp->srcu_gp_mutex);
mutex_unlock(&ssp->srcu_sup->srcu_gp_mutex);
return; /* Someone else started the grace period. */
}
}
@ -1619,7 +1619,7 @@ static void srcu_advance_state(struct srcu_struct *ssp)
if (rcu_seq_state(READ_ONCE(ssp->srcu_gp_seq)) == SRCU_STATE_SCAN1) {
idx = 1 ^ (ssp->srcu_idx & 1);
if (!try_check_zero(ssp, idx, 1)) {
mutex_unlock(&ssp->srcu_gp_mutex);
mutex_unlock(&ssp->srcu_sup->srcu_gp_mutex);
return; /* readers present, retry later. */
}
srcu_flip(ssp);
@ -1637,7 +1637,7 @@ static void srcu_advance_state(struct srcu_struct *ssp)
*/
idx = 1 ^ (ssp->srcu_idx & 1);
if (!try_check_zero(ssp, idx, 2)) {
mutex_unlock(&ssp->srcu_gp_mutex);
mutex_unlock(&ssp->srcu_sup->srcu_gp_mutex);
return; /* readers present, retry later. */
}
ssp->srcu_n_exp_nodelay = 0;