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The controlling process can request the collection of certain statistics about a target process. Statistics gathering is disabled by default. Each target process has a td_ta_stats_t structure that contains current values when statistic gathering is enabled.
The td_ta_enable_stats() function turns statistics gathering on or off for the process identified by ta_p, depending on whether or not on_off is non-zero. When statistics gathering is turned on, all statistics are implicitly reset
as though td_ta_reset_stats() had been called. Statistics are not reset when statistics gathering is turned off. Except for nthreads and r_concurrency, the values do not change further, but they remain available for inspection
by way of td_ta_get_stats().
The td_ta_reset_stats() function resets all counters in the td_ta_stats_t structure to zero for the target process.
The td_ta_get_stats() function returns the structure for the process in tstats.
The td_ta_stats_t structure is defined in <thread_db.h> and contains the following members:
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typedef struct {
int nthreads; /* total number of threads in use */
int r_concurrency; /* requested concurrency level */
int nrunnable_num; /* numerator of avg runnable threads */
int nrunnable_den; /* denominator of avg runnable threads */
int a_concurrency_num; /* numerator, avg achieved concurrency */
int a_concurrency_den; /* denominator, avg achieved concurrency */
int nlwps_num; /* numerator, avg number of LWPs in use */
int nlwps_den; /* denominator, avg number of LWPs in use */
int nidle_num; /* numerator, avg number of idling LWPs */
int nidle_den; /* denominator, avg number of idling LWPs */
} td_ta_stats_t;
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The nthreads member is the number of threads that are currently part of the target process. The r_concurrency member is the current requested concurrency level, such as would be returned by thr_setconcurrency(3THR). The remaining members are averages over time, each expressed as a fraction with an integral numerator and denominator. The nrunnable_num and nrunnable_den members represent the average
number of runnable threads. The a_concurrency_num and a_concurrency_den members represent the average achieved concurrency, the number of actually running threads. The a_concurrency_num and a_concurrency_den members are less
than or equal to nrunnable_num and nrunnable_den, respectively. The nlwps_num and nlwps_den members represent the average number of lightweight processes ( LWPs) participating in this process.
They must be greater than or equal to a_concurrency_num and a_concurrency_den, respectively, since every running thread is assigned to an LWP, but there can at times be additional idling LWPs with
no thread assigned to them. The nidle_num and nidle_den members represent the average number of idle LWPs.
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