Clamp update interval to reduce PLL gain with low sampling rate (e.g.
intermittent network connection) to avoid instability.
The clamp roughly corresponds to the loop time constant, it's 8 * poll
interval for SHIFT_PLL 2 and 32 * poll interval for SHIFT_PLL 4. This
gives good results without affecting the gain in normal conditions where
ntpd skips only up to seven consecutive samples.
Signed-off-by: Miroslav Lichvar <[email protected]>
Acked-by: john stultz <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
8af3c153ba