From: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
To: John Stultz <john.stultz@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Stephen Boyd <sboyd@kernel.org>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH v2] timer: Use static_branch_likely() for timers_nohz_active
Date: Thu, 24 Jun 2021 16:32:18 +0800 [thread overview]
Message-ID: <20210624163218.39ae3ec6@xhacker.debian> (raw)
The static key timers_nohz_active is likely to be true, so use
static_branch_likely() to reflect this fact.
Per include/linux/jump_label.h:
* type\branch| likely (1) | unlikely (0)
* -----------+-----------------------+------------------
* | |
* true (1) | ... | ...
* | NOP | JMP L
* | <br-stmts> | 1: ...
* | L: ... |
* | |
* | | L: <br-stmts>
* | | jmp 1b
* | |
* -----------+-----------------------+------------------
This could improve the finally generated code a bit for the most likely
scenario, I.E save two "jmp" instructions.
Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
Since v1:
- update the commit msg to avoid confusing and add some descriptions about
where's the improvement from.
kernel/time/timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index d111adf4a0cb..40d4fe7fa207 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -265,7 +265,7 @@ int timer_migration_handler(struct ctl_table *table, int write,
static inline bool is_timers_nohz_active(void)
{
- return static_branch_unlikely(&timers_nohz_active);
+ return static_branch_likely(&timers_nohz_active);
}
#else
static inline bool is_timers_nohz_active(void) { return false; }
--
2.31.0
next reply other threads:[~2021-06-24 8:32 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 8:32 Jisheng Zhang [this message]
2021-08-10 16:00 ` [PATCH v2] timer: Use static_branch_likely() for timers_nohz_active Thomas Gleixner
2021-08-20 10:18 ` Jisheng Zhang
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