Commit-ID: 3c2e79f4cef7938125b356e7f5c8fd038212619a Gitweb: https://git.kernel.org/tip/3c2e79f4cef7938125b356e7f5c8fd038212619a Author: Daniel Lezcano <daniel.lezc...@linaro.org> AuthorDate: Mon, 27 May 2019 22:55:16 +0200 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Wed, 12 Jun 2019 10:47:03 +0200
genirq/timings: Optimize the period detection speed With a minimal period and if there is a period which is a multiple of it but lesser than the max period then it will be detected before and the minimal period will be never reached. 1 2 1 2 1 2 1 2 1 2 1 2 <-----> <-----> <-----> <-> <-> <-> <-> <-> <-> In that case, the minimum period is 2 and the maximum period is 5. That means all repeating pattern of 2 will be detected as repeating pattern of 4, it is pointless to go up to 2 when searching for the period as it will always fail. Remove one loop iteration by increasing the minimal period to 3. Signed-off-by: Daniel Lezcano <daniel.lezc...@linaro.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: andriy.shevche...@linux.intel.com Link: https://lkml.kernel.org/r/20190527205521.12091-4-daniel.lezc...@linaro.org --- kernel/irq/timings.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/irq/timings.c b/kernel/irq/timings.c index 19d2fad379ee..1d1c411d4cae 100644 --- a/kernel/irq/timings.c +++ b/kernel/irq/timings.c @@ -261,7 +261,7 @@ void irq_timings_disable(void) #define EMA_ALPHA_VAL 64 #define EMA_ALPHA_SHIFT 7 -#define PREDICTION_PERIOD_MIN 2 +#define PREDICTION_PERIOD_MIN 3 #define PREDICTION_PERIOD_MAX 5 #define PREDICTION_FACTOR 4 #define PREDICTION_MAX 10 /* 2 ^ PREDICTION_MAX useconds */
