diff options
author | Miroslav Lichvar <mlichvar@redhat.com> | 2018-12-03 13:59:41 +0100 |
---|---|---|
committer | Saeed Mahameed <saeedm@mellanox.com> | 2018-12-20 05:06:00 -0800 |
commit | 5d8678365c90b9ce1fd2243ff5ea562609f6cec1 (patch) | |
tree | 798e2b6811644dca8db59dd3783227fa1a170ee7 /drivers | |
parent | a9cd3439e3c6d777a05c63b4d06c3500d1d4074e (diff) | |
download | linux-5d8678365c90b9ce1fd2243ff5ea562609f6cec1.tar.bz2 |
mlx5: update timecounter at least twice per counter overflow
The timecounter needs to be updated at least once in half of the
cyclecounter interval to prevent timecounter_cyc2time() interpreting a
new timestamp as an old value and causing a backward jump.
This would be an issue if the timecounter multiplier was so small that
the update interval would not be limited by the 64-bit overflow in
multiplication.
Shorten the calculated interval to make sure the timecounter is updated
in time even when the system clock is slowed down by up to 10%, the
multiplier is increased by up to 10%, and the scheduled overflow check
is late by 15%.
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Ariel Levkovich <lariel@mellanox.com>
Cc: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c index d27c239e7d6c..53f021df4934 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/clock.c @@ -517,14 +517,14 @@ void mlx5_init_clock(struct mlx5_core_dev *mdev) ktime_to_ns(ktime_get_real())); /* Calculate period in seconds to call the overflow watchdog - to make - * sure counter is checked at least once every wrap around. + * sure counter is checked at least twice every wrap around. * The period is calculated as the minimum between max HW cycles count * (The clock source mask) and max amount of cycles that can be * multiplied by clock multiplier where the result doesn't exceed * 64bits. */ overflow_cycles = div64_u64(~0ULL >> 1, clock->cycles.mult); - overflow_cycles = min(overflow_cycles, clock->cycles.mask >> 1); + overflow_cycles = min(overflow_cycles, div_u64(clock->cycles.mask, 3)); ns = cyclecounter_cyc2ns(&clock->cycles, overflow_cycles, frac, &frac); |