Messages in this thread Patch in this message | | | Date | Mon, 21 Dec 2009 12:21:21 -0800 | From | Stephen Hemminger <> | Subject | Re: 2.6.32.2: undefined reference to `__udivdi3' |
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The new menu governor driver is written by Intel folks who never use 32-bit anymore it seems :-) --------------------------------------------------------- Subject: [PATCH] menu: use proper 64 bit math
The new menu governor is incorrectly doing a 64 bit divide. Compile tested only
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
--- a/drivers/cpuidle/governors/menu.c 2009-12-21 12:02:25.840083589 -0800 +++ b/drivers/cpuidle/governors/menu.c 2009-12-21 12:16:42.418834255 -0800 @@ -18,6 +18,7 @@ #include <linux/hrtimer.h> #include <linux/tick.h> #include <linux/sched.h> +#include <linux/math64.h> #define BUCKETS 12 #define RESOLUTION 1024 @@ -169,6 +170,12 @@ static DEFINE_PER_CPU(struct menu_device static void menu_update(struct cpuidle_device *dev); +/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */ +static u64 div_round64(u64 dividend, u32 divisor) +{ + return div_u64(dividend + (divisor / 2), divisor); +} + /** * menu_select - selects the next idle state to enter * @dev: the CPU @@ -209,9 +216,8 @@ static int menu_select(struct cpuidle_de data->correction_factor[data->bucket] = RESOLUTION * DECAY; /* Make sure to round up for half microseconds */ - data->predicted_us = DIV_ROUND_CLOSEST( - data->expected_us * data->correction_factor[data->bucket], - RESOLUTION * DECAY); + data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket], + RESOLUTION * DECAY); /* * We want to default to C1 (hlt), not to busy polling
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