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Message-Id: <20190527205521.12091-4-daniel.lezcano@linaro.org> Date: Mon, 27 May 2019 22:55:16 +0200 From: Daniel Lezcano <daniel.lezcano@...aro.org> To: tglx@...utronix.de Cc: linux-kernel@...r.kernel.org, andriy.shevchenko@...ux.intel.com Subject: [PATCH V3 3/8] genirq/timings: Optimize the period detection speed If we have 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 our 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.lezcano@...aro.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 */ -- 2.17.1
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