trace_uprobe->nhit counter is not incremented atomically, so its value
is bogus in practice. On the other hand, it's actually a pretty big
uprobe scalability problem due to heavy cache line bouncing between CPUs
triggering the same uprobe.
Drop it and emit obviously unrealistic value in its stead in
uporbe_profiler seq file.
The alternative would be allocating per-CPU counter, but I'm not sure
it's justified.
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
---
kernel/trace/trace_uprobe.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 52e76a73fa7c..5d38207db479 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -62,7 +62,6 @@ struct trace_uprobe {
struct uprobe *uprobe;
unsigned long offset;
unsigned long ref_ctr_offset;
- unsigned long nhit;
struct trace_probe tp;
};
@@ -821,7 +820,7 @@ static int probes_profile_seq_show(struct seq_file *m, void *v)
tu = to_trace_uprobe(ev);
seq_printf(m, " %s %-44s %15lu\n", tu->filename,
- trace_probe_name(&tu->tp), tu->nhit);
+ trace_probe_name(&tu->tp), ULONG_MAX);
return 0;
}
@@ -1507,7 +1506,6 @@ static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs)
int ret = 0;
tu = container_of(con, struct trace_uprobe, consumer);
- tu->nhit++;
udd.tu = tu;
udd.bp_addr = instruction_pointer(regs);
--
2.43.5
