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Configurable sampling interval and call-stack tracing depth #80

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Configurable sampling interval and call-stack tracing depth #80

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34 changes: 28 additions & 6 deletions extension/xhprof.c
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Original file line number Diff line number Diff line change
Expand Up @@ -101,7 +101,8 @@
#define XHPROF_FLAGS_MEMORY 0x0004 /* gather memory usage for funcs */

/* Constants for XHPROF_MODE_SAMPLED */
#define XHPROF_SAMPLING_INTERVAL 100000 /* In microsecs */
#define XHPROF_DEFAULT_SAMPLING_INTERVAL 100000 /* In microsecs */
#define XHPROF_MINIMAL_SAMPLING_INTERVAL 100 /* In microsecs */

/* Constant for ignoring functions, transparent to hierarchical profile */
#define XHPROF_MAX_IGNORED_FUNCTIONS 256
Expand Down Expand Up @@ -193,8 +194,10 @@ typedef struct hp_global_t {
/* Global to track the time of the last sample in time and ticks */
struct timeval last_sample_time;
uint64 last_sample_tsc;
/* XHPROF_SAMPLING_INTERVAL in ticks */
long sampling_interval;
/* sampling_interval in ticks */
uint64 sampling_interval_tsc;
int sampling_depth;

/* This array is used to store cpu frequencies for all available logical
* cpus. For now, we assume the cpu frequencies will not change for power
Expand Down Expand Up @@ -349,6 +352,9 @@ zend_module_entry xhprof_module_entry = {
STANDARD_MODULE_PROPERTIES
};

#define STRINGIFY_(X) #X
#define STRINGIFY(X) STRINGIFY_(X)

PHP_INI_BEGIN()

/* output directory:
Expand All @@ -359,6 +365,16 @@ PHP_INI_BEGIN()
*/
PHP_INI_ENTRY("xhprof.output_dir", "", PHP_INI_ALL, NULL)

/* sampling_interval:
* Sampling interval to be used by the sampling profiler, in microseconds.
*/
STD_PHP_INI_ENTRY("xhprof.sampling_interval", STRINGIFY(XHPROF_DEFAULT_SAMPLING_INTERVAL), PHP_INI_ALL, OnUpdateLong, sampling_interval, hp_global_t, hp_globals)

/* sampling_depth:
* Depth to trace call-chain by the sampling profiler
*/
STD_PHP_INI_ENTRY("xhprof.sampling_depth", STRINGIFY(INT_MAX), PHP_INI_ALL, OnUpdateLong, sampling_depth, hp_global_t, hp_globals)

PHP_INI_END()

/* Init module */
Expand Down Expand Up @@ -476,6 +492,10 @@ PHP_MINIT_FUNCTION(xhprof) {

hp_ignored_functions_filter_clear();

if (hp_globals.sampling_interval < XHPROF_MINIMAL_SAMPLING_INTERVAL) {
hp_globals.sampling_interval = XHPROF_MINIMAL_SAMPLING_INTERVAL;
}

#if defined(DEBUG)
/* To make it random number generator repeatable to ease testing. */
srand(0);
Expand Down Expand Up @@ -542,6 +562,8 @@ PHP_MINFO_FUNCTION(xhprof)
}

php_info_print_table_end();

DISPLAY_INI_ENTRIES();
}


Expand Down Expand Up @@ -1171,7 +1193,7 @@ void hp_sample_stack(hp_entry_t **entries TSRMLS_DC) {

/* Init stats in the global stats_count hashtable */
hp_get_function_stack(*entries,
INT_MAX,
hp_globals.sampling_depth,
symbol,
sizeof(symbol));

Expand Down Expand Up @@ -1207,7 +1229,7 @@ void hp_sample_check(hp_entry_t **entries TSRMLS_DC) {
hp_globals.last_sample_tsc += hp_globals.sampling_interval_tsc;

/* bump last_sample_time - HAS TO BE UPDATED BEFORE calling hp_sample_stack */
incr_us_interval(&hp_globals.last_sample_time, XHPROF_SAMPLING_INTERVAL);
incr_us_interval(&hp_globals.last_sample_time, hp_globals.sampling_interval);

/* sample the stack */
hp_sample_stack(entries TSRMLS_CC);
Expand Down Expand Up @@ -1493,7 +1515,7 @@ void hp_mode_sampled_init_cb(TSRMLS_D) {
/* Find the microseconds that need to be truncated */
gettimeofday(&hp_globals.last_sample_time, 0);
now = hp_globals.last_sample_time;
hp_trunc_time(&hp_globals.last_sample_time, XHPROF_SAMPLING_INTERVAL);
hp_trunc_time(&hp_globals.last_sample_time, hp_globals.sampling_interval);

/* Subtract truncated time from last_sample_tsc */
truncated_us = get_us_interval(&hp_globals.last_sample_time, &now);
Expand All @@ -1505,7 +1527,7 @@ void hp_mode_sampled_init_cb(TSRMLS_D) {

/* Convert sampling interval to ticks */
hp_globals.sampling_interval_tsc =
get_tsc_from_us(XHPROF_SAMPLING_INTERVAL, cpu_freq);
get_tsc_from_us(hp_globals.sampling_interval, cpu_freq);
}


Expand Down