linux-kernel - [PATCH 1/2] x86/tsc: Force inlining of cyc2ns bits

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Date:   Thu, 11 Oct 2018 12:38:26 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     mingo@...nel.org, tglx@...utronix.de
Cc:     linux-kernel@...r.kernel.org, hpa@...or.com, edumazet@...gle.com,
        eric.dumazet@...il.com, bp@...en8.de, peterz@...radead.org
Subject: [PATCH 1/2] x86/tsc: Force inlining of cyc2ns bits

Looking at the asm for native_sched_clock() I noticed we don't inline
enough. Mostly caused by sharing code with cyc2ns_read_begin(), which
we didn't used to do. So mark all that __force_inline to make it DTRT.

Fixes: 59eaef78bfea ("x86/tsc: Remodel cyc2ns to use seqcount_latch()")
Reported-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/kernel/tsc.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -57,7 +57,7 @@ struct cyc2ns {
 
 static DEFINE_PER_CPU_ALIGNED(struct cyc2ns, cyc2ns);
 
-void cyc2ns_read_begin(struct cyc2ns_data *data)
+void __always_inline cyc2ns_read_begin(struct cyc2ns_data *data)
 {
 	int seq, idx;
 
@@ -74,7 +74,7 @@ void cyc2ns_read_begin(struct cyc2ns_dat
 	} while (unlikely(seq != this_cpu_read(cyc2ns.seq.sequence)));
 }
 
-void cyc2ns_read_end(void)
+void __always_inline cyc2ns_read_end(void)
 {
 	preempt_enable_notrace();
 }
@@ -103,7 +103,7 @@ void cyc2ns_read_end(void)
  *                      -johnstul@...ibm.com "math is hard, lets go shopping!"
  */
 
-static inline unsigned long long cycles_2_ns(unsigned long long cyc)
+static __always_inline unsigned long long cycles_2_ns(unsigned long long cyc)
 {
 	struct cyc2ns_data data;
 	unsigned long long ns;