1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #ifndef GRPC_CORE_LIB_GPR_TIME_PRECISE_H
20 #define GRPC_CORE_LIB_GPR_TIME_PRECISE_H
21
22 #include <grpc/support/port_platform.h>
23
24 #include <grpc/impl/codegen/gpr_types.h>
25 #include <grpc/support/time.h>
26
27 // Depending on the platform gpr_get_cycle_counter() can have a resolution as
28 // low as a usec. Use other clock sources or gpr_precise_clock_now(),
29 // where you need high resolution clocks.
30 //
31 // Using gpr_get_cycle_counter() is preferred to using ExecCtx::Get()->Now()
32 // whenever possible.
33
34 #if GPR_CYCLE_COUNTER_CUSTOM
35 typedef int64_t gpr_cycle_counter;
36 gpr_cycle_counter gpr_get_cycle_counter();
37 #elif GPR_CYCLE_COUNTER_RDTSC_32
38 typedef int64_t gpr_cycle_counter;
gpr_get_cycle_counter()39 inline gpr_cycle_counter gpr_get_cycle_counter() {
40 int64_t ret;
41 __asm__ volatile("rdtsc" : "=A"(ret));
42 return ret;
43 }
44 #elif GPR_CYCLE_COUNTER_RDTSC_64
45 typedef int64_t gpr_cycle_counter;
gpr_get_cycle_counter()46 inline gpr_cycle_counter gpr_get_cycle_counter() {
47 uint64_t low, high;
48 __asm__ volatile("rdtsc" : "=a"(low), "=d"(high));
49 return (high << 32) | low;
50 }
51 #elif GPR_CYCLE_COUNTER_FALLBACK
52 // TODO(soheil): add support for mrs on Arm.
53
54 // Real time in micros.
55 typedef double gpr_cycle_counter;
56 gpr_cycle_counter gpr_get_cycle_counter();
57 #else
58 #error Must define exactly one of \
59 GPR_CYCLE_COUNTER_RDTSC_32, \
60 GPR_CYCLE_COUNTER_RDTSC_64, \
61 GPR_CYCLE_COUNTER_CUSTOM, or \
62 GPR_CYCLE_COUNTER_FALLBACK
63 #endif
64
65 void gpr_precise_clock_init(void);
66 void gpr_precise_clock_now(gpr_timespec* clk);
67 gpr_timespec gpr_cycle_counter_to_time(gpr_cycle_counter cycles);
68 gpr_timespec gpr_cycle_counter_sub(gpr_cycle_counter a, gpr_cycle_counter b);
69
70 #endif /* GRPC_CORE_LIB_GPR_TIME_PRECISE_H */
71