[RFC][PATCH 10/16] objtool: Resize insn_hash

Peter Zijlstra
2020-03-12T13:52:36Z

Perf shows we're spending a lot of time in find_insn() and the
statistics show we have around 3.2 million instruction. Increase the
hash table size to reduce the bucket load from around 50 to 3.

This shaves about 2s off of objtool on vmlinux.o runtime, down to 16s.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
tools/objtool/check.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -50,7 +50,7 @@ struct instruction {
struct objtool_file {
struct elf *elf;
struct list_head insn_list;
- DECLARE_HASHTABLE(insn_hash, 16);
+ DECLARE_HASHTABLE(insn_hash, 20);
bool ignore_unreachables, c_file, hints, rodata;
};