From: "Maciej W. Rozycki" macro@orcam.me.uk
[ Upstream commit 92067440f1311dfa4d77b57a9da6b3706f5da32e ]
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.... Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/time/sched_clock.c | 5 +++-- 1 file 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 = ' ';