linux-kernel - [PATCH v2 36/40] tracing: Remove lookups from tracing

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Message-Id: <4c3ada8f9d958a5a926bbfa812c816bf8e73764b.1504642143.git.tom.zanussi@linux.intel.com>
Date:   Tue,  5 Sep 2017 16:57:48 -0500
From:   Tom Zanussi <tom.zanussi@...ux.intel.com>
To:     rostedt@...dmis.org
Cc:     tglx@...utronix.de, mhiramat@...nel.org, namhyung@...nel.org,
        vedang.patel@...el.com, bigeasy@...utronix.de,
        joel.opensrc@...il.com, joelaf@...gle.com,
        mathieu.desnoyers@...icios.com, baohong.liu@...el.com,
        linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org,
        Tom Zanussi <tom.zanussi@...ux.intel.com>
Subject: [PATCH v2 36/40] tracing: Remove lookups from tracing_map hitcount

Lookups inflate the hitcount, making it essentially useless.  Only
inserts and updates should really affect the hitcount anyway, so
explicitly filter lookups out.

Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
---
 kernel/trace/tracing_map.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/tracing_map.c b/kernel/trace/tracing_map.c
index a4e5a56..f8e2338 100644
--- a/kernel/trace/tracing_map.c
+++ b/kernel/trace/tracing_map.c
@@ -538,7 +538,8 @@ static inline bool keys_match(void *key, void *test_key, unsigned key_size)
 		if (test_key && test_key == key_hash) {
 			if (entry->val &&
 			    keys_match(key, entry->val->key, map->key_size)) {
-				atomic64_inc(&map->hits);
+				if (!lookup_only)
+					atomic64_inc(&map->hits);
 				return entry->val;
 			} else if (unlikely(!entry->val)) {
 				/*
-- 
1.9.3