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srcu: Move ->srcu_size_state from srcu_struct to srcu_usage

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This commit moves the ->srcu_size_state 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 17:16:30 -07:00
parent 208f41b131
commit a0d8cbd382
2 changed files with 20 additions and 19 deletions
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2
include/linux/srcutree.h
View File

@ -64,13 +64,13 @@ struct srcu_usage {
struct srcu_node *node; /* Combining tree. */
struct srcu_node *level[RCU_NUM_LVLS + 1];
/* First node at each level. */
int srcu_size_state; /* Small-to-big transition state. */
};
/*
* Per-SRCU-domain structure, similar in function to rcu_state.
*/
struct srcu_struct {
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. */

37
kernel/rcu/srcutree.c
View File

@ -225,7 +225,7 @@ static bool init_srcu_struct_nodes(struct srcu_struct *ssp, gfp_t gfp_flags)
}
sdp->grpmask = 1 << (cpu - sdp->mynode->grplo);
}
smp_store_release(&ssp->srcu_size_state, SRCU_SIZE_WAIT_BARRIER);
smp_store_release(&ssp->srcu_sup->srcu_size_state, SRCU_SIZE_WAIT_BARRIER);
return true;
}
@ -240,7 +240,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
ssp->srcu_sup = kzalloc(sizeof(*ssp->srcu_sup), GFP_KERNEL);
if (!ssp->srcu_sup)
return -ENOMEM;
ssp->srcu_size_state = SRCU_SIZE_SMALL;
ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
ssp->srcu_sup->node = NULL;
mutex_init(&ssp->srcu_cb_mutex);
mutex_init(&ssp->srcu_gp_mutex);
@ -261,7 +261,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
init_srcu_struct_data(ssp);
ssp->srcu_gp_seq_needed_exp = 0;
ssp->srcu_last_gp_end = ktime_get_mono_fast_ns();
if (READ_ONCE(ssp->srcu_size_state) == SRCU_SIZE_SMALL && SRCU_SIZING_IS_INIT()) {
if (READ_ONCE(ssp->srcu_sup->srcu_size_state) == SRCU_SIZE_SMALL && SRCU_SIZING_IS_INIT()) {
if (!init_srcu_struct_nodes(ssp, GFP_ATOMIC)) {
if (!ssp->sda_is_static) {
free_percpu(ssp->sda);
@ -270,7 +270,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
return -ENOMEM;
}
} else {
WRITE_ONCE(ssp->srcu_size_state, SRCU_SIZE_BIG);
WRITE_ONCE(ssp->srcu_sup->srcu_size_state, SRCU_SIZE_BIG);
}
}
smp_store_release(&ssp->srcu_gp_seq_needed, 0); /* Init done. */
@ -315,7 +315,7 @@ EXPORT_SYMBOL_GPL(init_srcu_struct);
static void __srcu_transition_to_big(struct srcu_struct *ssp)
{
lockdep_assert_held(&ACCESS_PRIVATE(ssp, lock));
smp_store_release(&ssp->srcu_size_state, SRCU_SIZE_ALLOC);
smp_store_release(&ssp->srcu_sup->srcu_size_state, SRCU_SIZE_ALLOC);
}
/*
@ -326,10 +326,10 @@ static void srcu_transition_to_big(struct srcu_struct *ssp)
unsigned long flags;
/* Double-checked locking on ->srcu_size-state. */
if (smp_load_acquire(&ssp->srcu_size_state) != SRCU_SIZE_SMALL)
if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) != SRCU_SIZE_SMALL)
return;
spin_lock_irqsave_rcu_node(ssp, flags);
if (smp_load_acquire(&ssp->srcu_size_state) != SRCU_SIZE_SMALL) {
if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) != SRCU_SIZE_SMALL) {
spin_unlock_irqrestore_rcu_node(ssp, flags);
return;
}
@ -345,7 +345,7 @@ static void spin_lock_irqsave_check_contention(struct srcu_struct *ssp)
{
unsigned long j;
if (!SRCU_SIZING_IS_CONTEND() || ssp->srcu_size_state)
if (!SRCU_SIZING_IS_CONTEND() || ssp->srcu_sup->srcu_size_state)
return;
j = jiffies;
if (ssp->srcu_size_jiffies != j) {
@ -666,7 +666,7 @@ void cleanup_srcu_struct(struct srcu_struct *ssp)
}
kfree(ssp->srcu_sup->node);
ssp->srcu_sup->node = NULL;
ssp->srcu_size_state = SRCU_SIZE_SMALL;
ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
if (!ssp->sda_is_static) {
free_percpu(ssp->sda);
ssp->sda = NULL;
@ -770,7 +770,7 @@ static void srcu_gp_start(struct srcu_struct *ssp)
struct srcu_data *sdp;
int state;
if (smp_load_acquire(&ssp->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
sdp = per_cpu_ptr(ssp->sda, get_boot_cpu_id());
else
sdp = this_cpu_ptr(ssp->sda);
@ -880,7 +880,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
/* A new grace period can start at this point. But only one. */
/* Initiate callback invocation as needed. */
ss_state = smp_load_acquire(&ssp->srcu_size_state);
ss_state = smp_load_acquire(&ssp->srcu_sup->srcu_size_state);
if (ss_state < SRCU_SIZE_WAIT_BARRIER) {
srcu_schedule_cbs_sdp(per_cpu_ptr(ssp->sda, get_boot_cpu_id()),
cbdelay);
@ -940,7 +940,7 @@ static void srcu_gp_end(struct srcu_struct *ssp)
if (ss_state == SRCU_SIZE_ALLOC)
init_srcu_struct_nodes(ssp, GFP_KERNEL);
else
smp_store_release(&ssp->srcu_size_state, ss_state + 1);
smp_store_release(&ssp->srcu_sup->srcu_size_state, ss_state + 1);
}
}
@ -1002,7 +1002,7 @@ static void srcu_funnel_gp_start(struct srcu_struct *ssp, struct srcu_data *sdp,
unsigned long snp_seq;
/* Ensure that snp node tree is fully initialized before traversing it */
if (smp_load_acquire(&ssp->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
snp_leaf = NULL;
else
snp_leaf = sdp->mynode;
@ -1209,7 +1209,7 @@ static unsigned long srcu_gp_start_if_needed(struct srcu_struct *ssp,
* sequence number cannot wrap around in the meantime.
*/
idx = __srcu_read_lock_nmisafe(ssp);
ss_state = smp_load_acquire(&ssp->srcu_size_state);
ss_state = smp_load_acquire(&ssp->srcu_sup->srcu_size_state);
if (ss_state < SRCU_SIZE_WAIT_CALL)
sdp = per_cpu_ptr(ssp->sda, get_boot_cpu_id());
else
@ -1546,7 +1546,7 @@ void srcu_barrier(struct srcu_struct *ssp)
atomic_set(&ssp->srcu_barrier_cpu_cnt, 1);
idx = __srcu_read_lock_nmisafe(ssp);
if (smp_load_acquire(&ssp->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
if (smp_load_acquire(&ssp->srcu_sup->srcu_size_state) < SRCU_SIZE_WAIT_BARRIER)
srcu_barrier_one_cpu(ssp, per_cpu_ptr(ssp->sda, get_boot_cpu_id()));
else
for_each_possible_cpu(cpu)
@ -1784,7 +1784,7 @@ void srcu_torture_stats_print(struct srcu_struct *ssp, char *tt, char *tf)
int cpu;
int idx;
unsigned long s0 = 0, s1 = 0;
int ss_state = READ_ONCE(ssp->srcu_size_state);
int ss_state = READ_ONCE(ssp->srcu_sup->srcu_size_state);
int ss_state_idx = ss_state;
idx = ssp->srcu_idx & 0x1;
@ -1871,8 +1871,9 @@ void __init srcu_init(void)
ssp = list_first_entry(&srcu_boot_list, struct srcu_struct,
work.work.entry);
list_del_init(&ssp->work.work.entry);
if (SRCU_SIZING_IS(SRCU_SIZING_INIT) && ssp->srcu_size_state == SRCU_SIZE_SMALL)
ssp->srcu_size_state = SRCU_SIZE_ALLOC;
if (SRCU_SIZING_IS(SRCU_SIZING_INIT) &&
ssp->srcu_sup->srcu_size_state == SRCU_SIZE_SMALL)
ssp->srcu_sup->srcu_size_state = SRCU_SIZE_ALLOC;
queue_work(rcu_gp_wq, &ssp->work.work);
}
}