diff options
Diffstat (limited to 'kernel/watchdog.c')
| -rw-r--r-- | kernel/watchdog.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 9c7134f7d2c4..5413aa85e8a4 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -425,7 +425,11 @@ static DEFINE_PER_CPU(u8, cpustat_tail); */ static u16 get_16bit_precision(u64 data_ns) { - return data_ns >> 24LL; /* 2^24ns ~= 16.8ms */ + /* + * 2^24ns ~= 16.8ms + * Round to the nearest multiple of 16.8 milliseconds. + */ + return (data_ns + (1 << 23)) >> 24LL; } static void update_cpustat(void) @@ -444,6 +448,14 @@ static void update_cpustat(void) old_stat = __this_cpu_read(cpustat_old[i]); new_stat = get_16bit_precision(cpustat[tracked_stats[i]]); util = DIV_ROUND_UP(100 * (new_stat - old_stat), sample_period_16); + /* + * Since we use 16-bit precision, the raw data will undergo + * integer division, which may sometimes result in data loss, + * and then result might exceed 100%. To avoid confusion, + * we enforce a 100% display cap when calculations exceed this threshold. + */ + if (util > 100) + util = 100; __this_cpu_write(cpustat_util[tail][i], util); __this_cpu_write(cpustat_old[i], new_stat); } |