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| author |  Nicolas Saenz Julienne <nsaenzju@redhat.com>
| 2021-07-21 13:47:26 +0200 |
|---|---|---|
| committer |  Steven Rostedt (VMware) <rostedt@goodmis.org>
| 2021-07-23 08:45:53 -0400 |
| commit | 68e83498cb4fad31963b5c76a71e80b824bc316e (patch) | |
| tree | 23ab37016b6548a6acd613d10a224243b9dc8cfd /kernel/trace | |
| parent | tracing: Clean up alloc_synth_event() (diff) | |
| download | linux-68e83498cb4fad31963b5c76a71e80b824bc316e.tar.gz linux-68e83498cb4fad31963b5c76a71e80b824bc316e.tar.bz2 linux-68e83498cb4fad31963b5c76a71e80b824bc316e.zip | |
ftrace: Avoid synchronize_rcu_tasks_rude() call when not necessary
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>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/ftrace.c | 3 |
1 files changed, 2 insertions, 1 deletions
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); } |