srcu: Move ->srcu_size_state from srcu_struct to srcu_usage

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>

diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index c7373fe5c14be7654fd62362491804ebb1cd2fa7..443d27a214ef9c7c4da4450b49b7f51aa9697c98 100644 (file)
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -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. */

diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
index acb0862faafa2e035d5feb4da9d82b211c414e54..8428a184d506b4f4b33c04bd2d3a97822c87404f 100644 (file)
--- a/kernel/rcu/srcutree.c
+++ b/kernel/rcu/srcutree.c
@@ -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);
        }
 }