diff options
| author | Maciej W. Rozycki <macro@orcam.me.uk> | 2022-04-24 12:47:20 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2022-05-02 14:29:04 +0200 |
| commit | 92067440f1311dfa4d77b57a9da6b3706f5da32e (patch) | |
| tree | f9ffe0b7acd783e727556651645b1d73cf4f9ea9 /kernel/time | |
| parent | 90be8d6c1f91e1e5121c219726524c91b52bfc20 (diff) | |
time/sched_clock: Round the frequency reported to nearest rather than down
The frequency reported for clock sources are rounded down, which gives
misleading figures, e.g.:
I/O ASIC clock frequency 24999480Hz
sched_clock: 32 bits at 24MHz, resolution 40ns, wraps every 85901132779ns
MIPS counter frequency 59998512Hz
sched_clock: 32 bits at 59MHz, resolution 16ns, wraps every 35792281591ns
Rounding to nearest is more adequate:
I/O ASIC clock frequency 24999664Hz
sched_clock: 32 bits at 25MHz, resolution 40ns, wraps every 85900499947ns
MIPS counter frequency 59999728Hz
sched_clock: 32 bits at 60MHz, resolution 16ns, wraps every 35791556599ns
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2204240055590.9383@angie.orcam.me.uk
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/sched_clock.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/time/sched_clock.c b/kernel/time/sched_clock.c index b1b9b12899f5..ee07f3ac1e5b 100644 --- a/kernel/time/sched_clock.c +++ b/kernel/time/sched_clock.c @@ -8,6 +8,7 @@ #include <linux/jiffies.h> #include <linux/ktime.h> #include <linux/kernel.h> +#include <linux/math.h> #include <linux/moduleparam.h> #include <linux/sched.h> #include <linux/sched/clock.h> @@ -199,11 +200,11 @@ sched_clock_register(u64 (*read)(void), int bits, unsigned long rate) r = rate; if (r >= 4000000) { - r /= 1000000; + r = DIV_ROUND_CLOSEST(r, 1000000); r_unit = 'M'; } else { if (r >= 1000) { - r /= 1000; + r = DIV_ROUND_CLOSEST(r, 1000); r_unit = 'k'; } else { r_unit = ' '; |