From: YOSHIFUJI Hideaki Date: Sun, 30 Oct 2005 01:15:42 +0000 (-0700) Subject: [PATCH] TIMERS: add missing compensation for HZ == 250 X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4b8f573b5db02a3017afbba49026a6aef480174f;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git [PATCH] TIMERS: add missing compensation for HZ == 250 Add missing compensation for (HZ == 250) != (1 << SHIFT_HZ) in second_overflow(). Signed-off-by: YOSHIFUJI Hideaki Cc: "David S. Miller" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/kernel/timer.c b/kernel/timer.c index 3ba10fa35b60..6a2e5f8dc725 100644 --- a/kernel/timer.c +++ b/kernel/timer.c @@ -752,6 +752,15 @@ static void second_overflow(void) else time_adj += (time_adj >> 2) + (time_adj >> 5); #endif +#if HZ == 250 + /* Compensate for (HZ==250) != (1 << SHIFT_HZ). + * Add 1.5625% and 0.78125% to get 255.85938; => only 0.05% error (p. 14) + */ + if (time_adj < 0) + time_adj -= (-time_adj >> 6) + (-time_adj >> 7); + else + time_adj += (time_adj >> 6) + (time_adj >> 7); +#endif #if HZ == 1000 /* Compensate for (HZ==1000) != (1 << SHIFT_HZ). * Add 1.5625% and 0.78125% to get 1023.4375; => only 0.05% error (p. 14)