Messages in this thread Patch in this message | | | Date | Fri, 23 Jul 2021 08:54:59 -0400 | From | Steven Rostedt <> | Subject | [for-linus][PATCH 5/7] ftrace: Avoid synchronize_rcu_tasks_rude() call when not necessary |
| |
From: Nicolas Saenz Julienne <nsaenzju@redhat.com>
synchronize_rcu_tasks_rude() triggers IPIs and forces rescheduling on all CPUs. It is a costly operation and, when targeting nohz_full CPUs, very disrupting (hence the name). So avoid calling it when 'old_hash' doesn't need to be freed.
Link: https://lkml.kernel.org/r/20210721114726.1545103-1-nsaenzju@redhat.com
Signed-off-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> --- kernel/trace/ftrace.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index e6fb3e6e1ffc..4fbcf560dd03 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -5985,7 +5985,8 @@ ftrace_graph_release(struct inode *inode, struct file *file) * infrastructure to do the synchronization, thus we must do it * ourselves. */ - synchronize_rcu_tasks_rude(); + if (old_hash != EMPTY_HASH) + synchronize_rcu_tasks_rude(); free_ftrace_hash(old_hash); } -- 2.30.2
| |