[tip: core/objtool] objtool: Resize insn_hash

[tip-bot2 for Peter Zijlstra]

The following commit has been merged into the core/objtool branch of tip:

Commit-ID:     513b5ca6b5fbeb766999fb1a4bc9a55c9fb7c9ca
Gitweb:        https://git.kernel.org/tip/513b5ca6b5fbeb766999fb1a4bc9a55c9fb7c9ca
Author:        Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate:    Thu, 12 Mar 2020 10:20:46 +01:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Wed, 25 Mar 2020 18:28:30 +01:00

objtool: Resize insn_hash

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@xxxxxxxxxxxxx>
Reviewed-by: Miroslav Benes <mbenes@xxxxxxx>
Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200324160924.617882545@xxxxxxxxxxxxx
---
 tools/objtool/check.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 6d875ca..f0ce8ff 100644
--- 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;
 };