From: Dipankar Sarma Finally, RCU gets its own softirq. With it being used extensively, the per-cpu tasklet used earlier was just a softirq with overheads. This makes things more efficient. Signed-off-by: Dipankar Sarma Acked-by: Paul E. McKenney Signed-off-by: Andrew Morton --- include/linux/interrupt.h | 1 + kernel/rcuclassic.c | 12 +++++------- 2 files changed, 6 insertions(+), 7 deletions(-) diff -puN include/linux/interrupt.h~rcu-softirq-for-rcu include/linux/interrupt.h --- a/include/linux/interrupt.h~rcu-softirq-for-rcu +++ a/include/linux/interrupt.h @@ -239,6 +239,7 @@ enum #ifdef CONFIG_HIGH_RES_TIMERS HRTIMER_SOFTIRQ, #endif + RCU_SOFTIRQ, }; /* softirq mask and active fields moved to irq_cpustat_t in diff -puN kernel/rcuclassic.c~rcu-softirq-for-rcu kernel/rcuclassic.c --- a/kernel/rcuclassic.c~rcu-softirq-for-rcu +++ a/kernel/rcuclassic.c @@ -69,7 +69,6 @@ DEFINE_PER_CPU(struct rcu_data, rcu_data DEFINE_PER_CPU(struct rcu_data, rcu_bh_data) = { 0L }; /* Fake initialization required by compiler */ -static DEFINE_PER_CPU(struct tasklet_struct, rcu_tasklet) = {NULL}; static int blimit = 10; static int qhimark = 10000; static int qlowmark = 100; @@ -215,7 +214,7 @@ static void rcu_do_batch(struct rcu_data if (!rdp->donelist) rdp->donetail = &rdp->donelist; else - tasklet_schedule(&per_cpu(rcu_tasklet, rdp->cpu)); + raise_softirq(RCU_SOFTIRQ); } /* @@ -367,7 +366,6 @@ static void rcu_offline_cpu(int cpu) &per_cpu(rcu_bh_data, cpu)); put_cpu_var(rcu_data); put_cpu_var(rcu_bh_data); - tasklet_kill_immediate(&per_cpu(rcu_tasklet, cpu), cpu); } #else @@ -379,7 +377,7 @@ static void rcu_offline_cpu(int cpu) #endif /* - * This does the RCU processing work from tasklet context. + * This does the RCU processing work from softirq context. */ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp, struct rcu_data *rdp) @@ -424,7 +422,7 @@ static void __rcu_process_callbacks(stru rcu_do_batch(rdp); } -static void rcu_process_callbacks(unsigned long unused) +static void rcu_process_callbacks(struct softirq_action *unused) { __rcu_process_callbacks(&rcu_ctrlblk, &__get_cpu_var(rcu_data)); __rcu_process_callbacks(&rcu_bh_ctrlblk, &__get_cpu_var(rcu_bh_data)); @@ -488,7 +486,7 @@ void rcu_check_callbacks(int cpu, int us rcu_bh_qsctr_inc(cpu); } else if (!in_softirq()) rcu_bh_qsctr_inc(cpu); - tasklet_schedule(&per_cpu(rcu_tasklet, cpu)); + raise_softirq(RCU_SOFTIRQ); } static void rcu_init_percpu_data(int cpu, struct rcu_ctrlblk *rcp, @@ -511,7 +509,7 @@ static void __devinit rcu_online_cpu(int rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp); rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp); - tasklet_init(&per_cpu(rcu_tasklet, cpu), rcu_process_callbacks, 0UL); + open_softirq(RCU_SOFTIRQ, rcu_process_callbacks, NULL); } static int __cpuinit rcu_cpu_notify(struct notifier_block *self, _