On Mon, Feb 26, 2018 at 12:15:14PM -0500, Steven Rostedt wrote: > On Mon, 26 Feb 2018 14:11:36 +0900 > Byungchul Park <byungchul.p...@lge.com> wrote: > > > rcu_preemptp_do_callback() was introduced in commit 09223371dea(rcu: > > Use softirq to address performance regression), where it had to be > > distinguished between in the case CONFIG_TREE_PREEMPT_RCU is set and > > it's not. > > > > Now that the code was cleaned up so that rcu_preemt_do_callback() is > > only called in rcu_kthread_do_work() in the same file, tree_plugin.h, > > we don't have to keep the separate function anymore. Remove it for a > > better readability. > > Looks good to me (looks like commit f8b7fc6b51 "rcu: use softirq > instead of kthreads except when RCU_BOOST=y" cleaned up the ifdefs and > removed the requirement). > > Reviewed-by: Steven Rostedt (VMware) <rost...@goodmis.org>
Thank you both! I have queued a slightly modified patch for testing and further review. Please see below and let me know if I messed something up. Thanx, Paul ------------------------------------------------------------------------ commit b8a3012ddba397d4a18d9fd4a00432f8c2626bd6 Author: Byungchul Park <byungchul.p...@lge.com> Date: Mon Feb 26 14:11:36 2018 +0900 rcu: Inline rcu_preempt_do_callback() into its sole caller The rcu_preempt_do_callbacks() function was introduced in commit 09223371dea(rcu: Use softirq to address performance regression), where it was necessary to handle kernel builds both containing and not containing RCU-preempt. Since then, various changes (most notably f8b7fc6b51 ("rcu: use softirq instead of kthreads except when RCU_BOOST=y")) have resulted in this function being invoked only from rcu_kthread_do_work(), which is present only in kernels containing RCU-preempt, which in turn means that the rcu_preempt_do_callbacks() function is no longer needed. This commit therefore inlines rcu_preempt_do_callbacks() into its sole remaining caller and also removes the rcu_state_p and rcu_data_p indirection for added clarity. Signed-off-by: Byungchul Park <byungchul.p...@lge.com> Reviewed-by: Steven Rostedt (VMware) <rost...@goodmis.org> [ paulmck: Remove the rcu_state_p and rcu_data_p indirection. ] diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h index dc6f2319fc21..9dd0ea77faed 100644 --- a/kernel/rcu/tree.h +++ b/kernel/rcu/tree.h @@ -449,7 +449,6 @@ static void rcu_preempt_boost_start_gp(struct rcu_node *rnp); static void invoke_rcu_callbacks_kthread(void); static bool rcu_is_callbacks_kthread(void); #ifdef CONFIG_RCU_BOOST -static void rcu_preempt_do_callbacks(void); static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp, struct rcu_node *rnp); #endif /* #ifdef CONFIG_RCU_BOOST */ diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h index 26d7a31e81cb..b0d7f9ba6bf2 100644 --- a/kernel/rcu/tree_plugin.h +++ b/kernel/rcu/tree_plugin.h @@ -686,15 +686,6 @@ static void rcu_preempt_check_callbacks(void) t->rcu_read_unlock_special.b.need_qs = true; } -#ifdef CONFIG_RCU_BOOST - -static void rcu_preempt_do_callbacks(void) -{ - rcu_do_batch(rcu_state_p, this_cpu_ptr(rcu_data_p)); -} - -#endif /* #ifdef CONFIG_RCU_BOOST */ - /** * call_rcu() - Queue an RCU callback for invocation after a grace period. * @head: structure to be used for queueing the RCU updates. @@ -1170,7 +1161,7 @@ static void rcu_kthread_do_work(void) { rcu_do_batch(&rcu_sched_state, this_cpu_ptr(&rcu_sched_data)); rcu_do_batch(&rcu_bh_state, this_cpu_ptr(&rcu_bh_data)); - rcu_preempt_do_callbacks(); + rcu_do_batch(&rcu_preempt_state, this_cpu_ptr(&rcu_preempt_data)); } static void rcu_cpu_kthread_setup(unsigned int cpu)