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    Subject[PATCH rcu 13/20] srcu: Move ->sda_is_static from srcu_struct to srcu_usage
    Date
    This commit moves the ->sda_is_static 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>
    Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
    ---
    include/linux/srcutree.h | 2 +-
    kernel/rcu/srcutree.c | 8 ++++----
    2 files changed, 5 insertions(+), 5 deletions(-)

    diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
    index 3023492d8d89..d3534ecb806e 100644
    --- a/include/linux/srcutree.h
    +++ b/include/linux/srcutree.h
    @@ -76,6 +76,7 @@ struct srcu_usage {
    unsigned long srcu_size_jiffies; /* Current contention-measurement interval. */
    unsigned long srcu_n_lock_retries; /* Contention events in current interval. */
    unsigned long srcu_n_exp_nodelay; /* # expedited no-delays in current GP phase. */
    + bool sda_is_static; /* May ->sda be passed to free_percpu()? */
    };

    /*
    @@ -84,7 +85,6 @@ struct srcu_usage {
    struct srcu_struct {
    unsigned int srcu_idx; /* Current rdr array element. */
    struct srcu_data __percpu *sda; /* Per-CPU srcu_data array. */
    - bool sda_is_static; /* May ->sda be passed to free_percpu()? */
    unsigned long srcu_barrier_seq; /* srcu_barrier seq #. */
    struct mutex srcu_barrier_mutex; /* Serialize barrier ops. */
    struct completion srcu_barrier_completion;
    diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c
    index 291fb520bce0..20f2373f7e25 100644
    --- a/kernel/rcu/srcutree.c
    +++ b/kernel/rcu/srcutree.c
    @@ -252,7 +252,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
    mutex_init(&ssp->srcu_barrier_mutex);
    atomic_set(&ssp->srcu_barrier_cpu_cnt, 0);
    INIT_DELAYED_WORK(&ssp->work, process_srcu);
    - ssp->sda_is_static = is_static;
    + ssp->srcu_sup->sda_is_static = is_static;
    if (!is_static)
    ssp->sda = alloc_percpu(struct srcu_data);
    if (!ssp->sda) {
    @@ -265,7 +265,7 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static)
    ssp->srcu_sup->srcu_last_gp_end = ktime_get_mono_fast_ns();
    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) {
    + if (!ssp->srcu_sup->sda_is_static) {
    free_percpu(ssp->sda);
    ssp->sda = NULL;
    kfree(ssp->srcu_sup);
    @@ -667,7 +667,7 @@ void cleanup_srcu_struct(struct srcu_struct *ssp)
    kfree(ssp->srcu_sup->node);
    ssp->srcu_sup->node = NULL;
    ssp->srcu_sup->srcu_size_state = SRCU_SIZE_SMALL;
    - if (!ssp->sda_is_static) {
    + if (!ssp->srcu_sup->sda_is_static) {
    free_percpu(ssp->sda);
    ssp->sda = NULL;
    kfree(ssp->srcu_sup);
    @@ -1906,7 +1906,7 @@ static void srcu_module_going(struct module *mod)
    for (i = 0; i < mod->num_srcu_structs; i++) {
    ssp = *(sspp++);
    if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_sup->srcu_gp_seq_needed)) &&
    - !WARN_ON_ONCE(!ssp->sda_is_static))
    + !WARN_ON_ONCE(!ssp->srcu_sup->sda_is_static))
    cleanup_srcu_struct(ssp);
    free_percpu(ssp->sda);
    }
    --
    2.40.0.rc2
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