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334 lines
12 KiB
334 lines
12 KiB
/*
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* Prof
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* ====
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*
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* Self-contained C/C++ profiler library for Linux.
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*
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* Prof offers a quick way to measure performance events (CPU clock cycles,
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* cache misses, branch mispredictions, etc.) of C/C++ code snippets. Prof is
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* just a wrapper around the `perf_event_open` system call, its main goal is to
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* be easy to setup and painless to use for targeted optimizations, namely, when
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* the hot spot has already been identified. In no way Prof is a replacement for
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* a fully-fledged profiler like perf, gprof, callgrind, etc.
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*
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* Please be aware that Prof uses `__attribute__((constructor))` to be as more
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* straightforward to setup as possible, so it cannot be included more than
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* once.
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*
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* Examples
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* --------
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*
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* ### Minimal
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*
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* The following snippet prints the rough number of CPU clock cycles spent in
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* executing the code between the two Prof calls:
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*
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* ```c
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* #include "prof.h"
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*
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* int main()
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* {
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* PROF_START();
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* // slow code goes here...
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* PROF_STDOUT();
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* }
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* ```
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*
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* ### Custom options
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*
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* The following snippet instead counts both read and write faults of the level
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* 1 data cache that occur in the userland code between the two Prof calls:
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*
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* ```c
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* #include <stdio.h>
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*
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* #define PROF_USER_EVENTS_ONLY
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* #define PROF_EVENT_LIST \
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* PROF_EVENT_CACHE(L1D, READ, MISS) \
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* PROF_EVENT_CACHE(L1D, WRITE, MISS)
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* #include "prof.h"
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*
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* int main()
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* {
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* uint64_t faults[2] = { 0 };
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*
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* PROF_START();
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* // slow code goes here...
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* PROF_DO(faults[index] += counter);
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*
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* // fast or uninteresting code goes here...
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*
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* PROF_START();
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* // slow code goes here...
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* PROF_DO(faults[index] += counter);
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*
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* printf("Total L1 faults: R = %lu; W = %lu\n", faults[0], faults[1]);
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* }
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* ```
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*
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* Installation
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* ------------
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*
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* Just include `prof.h`. Here is a quick way to fetch the latest version:
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*
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* wget -q https://raw.githubusercontent.com/cyrus-and/prof/master/prof.h
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*/
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#ifndef PROF_H
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#define PROF_H
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#include <errno.h>
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#include <linux/perf_event.h>
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#include <stdarg.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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/*
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* API
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* ---
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*/
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/*
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* Reset the counters and (re)start counting the events.
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*
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* The events to be monitored are specified by setting the `PROF_EVENT_LIST`
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* macro before including this file to a list of `PROF_EVENT_*` invocations;
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* defaults to counting the number CPU clock cycles.
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*
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* If the `PROF_USER_EVENTS_ONLY` macro is defined before including this file
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* then kernel and hypervisor events are excluded from the count.
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*/
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#define PROF_START() \
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do { \
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PROF_IOCTL_(ENABLE); \
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PROF_IOCTL_(RESET); \
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} while (0)
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/*
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* Specify an event to be monitored, `type` and `config` are defined in the
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* documentation of the `perf_event_open` system call.
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*/
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#define PROF_EVENT(type, config) \
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(uint32_t)(type), (uint64_t)(config),
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/*
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* Same as `PROF_EVENT` but for hardware events; prefix `PERF_COUNT_HW_` must be
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* omitted from `config`.
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*/
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#define PROF_EVENT_HW(config) \
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PROF_EVENT(PERF_TYPE_HARDWARE, PERF_COUNT_HW_ ## config)
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/*
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* Same as `PROF_EVENT` but for software events; prefix `PERF_COUNT_SW_` must be
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* omitted from `config`.
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*/
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#define PROF_EVENT_SW(config) \
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PROF_EVENT(PERF_TYPE_SOFTWARE, PERF_COUNT_SW_ ## config)
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/*
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* Same as `PROF_EVENT` but for cache events; prefixes `PERF_COUNT_HW_CACHE_`,
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* `PERF_COUNT_HW_CACHE_OP_` and `PERF_COUNT_HW_CACHE_RESULT_` must be omitted
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* from `cache`, `op` and `result`, respectively. Again `cache`, `op` and
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* `result` are defined in the documentation of the `perf_event_open` system
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* call.
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*/
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#define PROF_EVENT_CACHE(cache, op, result) \
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PROF_EVENT(PERF_TYPE_HW_CACHE, \
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(PERF_COUNT_HW_CACHE_ ## cache) | \
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(PERF_COUNT_HW_CACHE_OP_ ## op << 8) | \
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(PERF_COUNT_HW_CACHE_RESULT_ ## result << 16))
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/*
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* Stop counting the events. The counter array can then be accessed with
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* `PROF_COUNTERS`.
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*/
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#define PROF_STOP() \
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do { \
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PROF_IOCTL_(DISABLE); \
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PROF_READ_COUNTERS_(prof_event_buf_); \
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} while (0)
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/*
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* Access the counter array. The order of counters is the same of the events
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* defined in `PROF_EVENT_LIST`. Elements of this array are 64 bit unsigned
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* integers.
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*/
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#define PROF_COUNTERS \
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(prof_event_buf_ + 1)
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/*
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* Stop counting the events and execute the code provided by `block` for each
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* event. Within `code`: `index` refers to the event position index in the
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* counter array defined by `PROF_COUNTERS`; `counter` is the actual value of
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* the counter. `index` is a 64 bit unsigned integer.
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*/
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#define PROF_DO(block) \
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do { \
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uint64_t i_; \
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PROF_STOP(); \
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for (i_ = 0; i_ < prof_event_cnt_; i_++) { \
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uint64_t index = i_; \
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uint64_t counter = prof_event_buf_[i_ + 1]; \
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(void)index; \
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(void)counter; \
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block; \
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} \
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} while (0)
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/*
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* Same as `PROF_DO` except that `callback` is the name of a *callable* object
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* (e.g. a function) which, for each event, is be called with the two parameters
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* `index` and `counter`.
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*/
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#define PROF_CALL(callback) \
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PROF_DO(callback(index, counter))
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/*
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* Stop counting the events and write to `file` (a stdio.h `FILE *`) as many
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* lines as are events in `PROF_EVENT_LIST`. Each line contains `index` and
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* `counter` (as defined by `PROF_DO`) separated by a tabulation character. If
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* there is only one event then `index` is omitted.
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*/
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#define PROF_FILE(file) \
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PROF_DO(if (prof_event_cnt_ > 1) { \
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fprintf((file), "%lu\t%lu\n", index, counter); \
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} else { \
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fprintf((file), "%lu\n", counter); \
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} \
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)
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/*
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* Same as `PROF_LOG_FILE` except that `file` is `stdout`.
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*/
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#define PROF_STDOUT() \
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PROF_FILE(stdout)
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/*
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* Same as `PROF_LOG_FILE` except that `file` is `stderr`.
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*/
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#define PROF_STDERR() \
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PROF_FILE(stderr)
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/* DEFAULTS ----------------------------------------------------------------- */
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#ifndef PROF_EVENT_LIST
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#ifdef PERF_COUNT_HW_REF_CPU_CYCLES /* since Linux 3.3 */
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#define PROF_EVENT_LIST PROF_EVENT_HW(REF_CPU_CYCLES)
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#else
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#define PROF_EVENT_LIST PROF_EVENT_HW(CPU_CYCLES)
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#endif
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#endif
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/* UTILITY ------------------------------------------------------------------ */
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#define PROF_ASSERT_(x) \
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do { \
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if (!(x)) { \
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fprintf(stderr, "# %s:%d: PROF error", __FILE__, __LINE__); \
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if (errno) { \
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fprintf(stderr, " (%s)", strerror(errno)); \
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} \
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printf("\n"); \
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abort(); \
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} \
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} while (0)
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#define PROF_IOCTL_(mode) \
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do { \
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PROF_ASSERT_(ioctl(prof_fd_, \
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PERF_EVENT_IOC_ ## mode, \
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PERF_IOC_FLAG_GROUP) != -1); \
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} while (0)
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#define PROF_READ_COUNTERS_(buffer) \
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do { \
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const ssize_t to_read = sizeof(uint64_t) * (prof_event_cnt_ + 1); \
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PROF_ASSERT_(read(prof_fd_, buffer, to_read) == to_read); \
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} while (0)
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/* SETUP -------------------------------------------------------------------- */
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static int prof_fd_;
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static uint64_t prof_event_cnt_;
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static uint64_t *prof_event_buf_;
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static void prof_init_(uint64_t dummy, ...) {
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uint32_t type;
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va_list ap;
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prof_fd_ = -1;
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prof_event_cnt_ = 0;
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va_start(ap, dummy);
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while (type = va_arg(ap, uint32_t), type != (uint32_t)-1) {
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struct perf_event_attr pe;
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uint64_t config;
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int fd;
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config = va_arg(ap, uint64_t);
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memset(&pe, 0, sizeof(struct perf_event_attr));
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pe.size = sizeof(struct perf_event_attr);
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pe.read_format = PERF_FORMAT_GROUP;
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pe.type = type;
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pe.config = config;
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#ifdef PROF_USER_EVENTS_ONLY
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pe.exclude_kernel = 1;
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pe.exclude_hv = 1;
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#endif
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fd = syscall(__NR_perf_event_open, &pe, 0, -1, prof_fd_, 0);
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PROF_ASSERT_(fd != -1);
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if (prof_fd_ == -1) {
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prof_fd_ = fd;
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}
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prof_event_cnt_++;
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}
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va_end(ap);
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prof_event_buf_ = (uint64_t *)malloc((prof_event_cnt_ + 1) *
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sizeof(uint64_t));
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}
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void __attribute__((constructor)) prof_init()
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{
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prof_init_(0, PROF_EVENT_LIST /*,*/ (uint32_t)-1);
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}
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void __attribute__((destructor)) prof_fini()
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{
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PROF_ASSERT_(close(prof_fd_) != -1);
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free(prof_event_buf_);
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}
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#endif
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/*
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* License
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* -------
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*
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* Copyright (c) 2017 Andrea Cardaci <cyrus.and@gmail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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