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));
