kern_tc.c (3d9d64aa1846217eac9229f8cba5cb6646a688b7) kern_tc.c (bb53dd56c30c6360fc82be762ed98b0af6b9f69f)
1/*-
2 * SPDX-License-Identifier: Beerware
3 *
4 * ----------------------------------------------------------------------------
5 * "THE BEER-WARE LICENSE" (Revision 42):
6 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
7 * can do whatever you want with this stuff. If we meet some day, and you think
8 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp

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2150}
2151
2152/*
2153 * We need to be slightly careful converting cputicks to microseconds.
2154 * There is plenty of margin in 64 bits of microseconds (half a million
2155 * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
2156 * before divide conversion (to retain precision) we find that the
2157 * margin shrinks to 1.5 hours (one millionth of 146y).
1/*-
2 * SPDX-License-Identifier: Beerware
3 *
4 * ----------------------------------------------------------------------------
5 * "THE BEER-WARE LICENSE" (Revision 42):
6 * <phk@FreeBSD.ORG> wrote this file. As long as you retain this notice you
7 * can do whatever you want with this stuff. If we meet some day, and you think
8 * this stuff is worth it, you can buy me a beer in return. Poul-Henning Kamp

--- 2141 unchanged lines hidden (view full) ---

2150}
2151
2152/*
2153 * We need to be slightly careful converting cputicks to microseconds.
2154 * There is plenty of margin in 64 bits of microseconds (half a million
2155 * years) and in 64 bits at 4 GHz (146 years), but if we do a multiply
2156 * before divide conversion (to retain precision) we find that the
2157 * margin shrinks to 1.5 hours (one millionth of 146y).
2158 * With a three prong approach we never lose significant bits, no
2159 * matter what the cputick rate and length of timeinterval is.
2160 */
2161
2162uint64_t
2163cputick2usec(uint64_t tick)
2164{
2158 */
2159
2160uint64_t
2161cputick2usec(uint64_t tick)
2162{
2165
2166 if (tick > 18446744073709551LL) /* floor(2^64 / 1000) */
2167 return (tick / (cpu_tickrate() / 1000000LL));
2168 else if (tick > 18446744073709LL) /* floor(2^64 / 1000000) */
2169 return ((tick * 1000LL) / (cpu_tickrate() / 1000LL));
2170 else
2171 return ((tick * 1000000LL) / cpu_tickrate());
2163 uint64_t tr;
2164 tr = cpu_tickrate();
2165 return ((tick / tr) * 1000000ULL) + ((tick % tr) * 1000000ULL) / tr;
2172}
2173
2174cpu_tick_f *cpu_ticks = tc_cpu_ticks;
2175
2176static int vdso_th_enable = 1;
2177static int
2178sysctl_fast_gettime(SYSCTL_HANDLER_ARGS)
2179{

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2167
2168cpu_tick_f *cpu_ticks = tc_cpu_ticks;
2169
2170static int vdso_th_enable = 1;
2171static int
2172sysctl_fast_gettime(SYSCTL_HANDLER_ARGS)
2173{

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