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Commit b663a79c authored by Maxim Uvarov's avatar Maxim Uvarov Committed by Linus Torvalds
Browse files

taskstats: add context-switch counters 



Make available to the user the following task and process performance
statistics:

	* Involuntary Context Switches (task_struct->nivcsw)
	* Voluntary Context Switches (task_struct->nvcsw)

Statistics information is available from:
	1. taskstats interface (Documentation/accounting/)
	2. /proc/PID/status (task only).

This data is useful for detecting hyperactivity patterns between processes.

[akpm@linux-foundation.org: cleanup]
Signed-off-by: default avatarMaxim Uvarov <muvarov@ru.mvista.com>
Cc: Shailabh Nagar <nagar@watson.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Jay Lan <jlan@engr.sgi.com>
Cc: Jonathan Lim <jlim@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a6c15c2b

Documentation/accounting/getdelays.c

+17 −2
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ char name[100]; 
int dbg;

int print_delays;

int print_io_accounting;

int print_task_context_switch_counts;

__u64 stime, utime;



#define PRINTF(fmt, arg...) {			\
@@ -195,7 +196,7 @@ void print_delayacct(struct taskstats *t) 
	       "IO    %15s%15s\n"

	       "      %15llu%15llu\n"

	       "MEM   %15s%15s\n"

	       "      %15llu%15llu\n\n",

	       "      %15llu%15llu\n"

	       "count", "real total", "virtual total", "delay total",

	       t->cpu_count, t->cpu_run_real_total, t->cpu_run_virtual_total,

	       t->cpu_delay_total,
@@ -204,6 +205,14 @@ void print_delayacct(struct taskstats *t) 
	       "count", "delay total", t->swapin_count, t->swapin_delay_total);

}



void task_context_switch_counts(struct taskstats *t)

{

	printf("\n\nTask   %15s%15s\n"

	       "       %15lu%15lu\n",

	       "voluntary", "nonvoluntary",

	       t->nvcsw, t->nivcsw);

}



void print_ioacct(struct taskstats *t)

{

	printf("%s: read=%llu, write=%llu, cancelled_write=%llu\n",
@@ -235,7 +244,7 @@ int main(int argc, char *argv[]) 
	struct msgtemplate msg;



	while (1) {

		c = getopt(argc, argv, "diw:r:m:t:p:vl");

		c = getopt(argc, argv, "qdiw:r:m:t:p:vl");

		if (c < 0)

			break;
@@ -248,6 +257,10 @@ int main(int argc, char *argv[]) 
			printf("printing IO accounting\n");

			print_io_accounting = 1;

			break;

		case 'q':

			printf("printing task/process context switch rates\n");

			print_task_context_switch_counts = 1;

			break;

		case 'w':

			logfile = strdup(optarg);

			printf("write to file %s\n", logfile);
@@ -389,6 +402,8 @@ int main(int argc, char *argv[]) 
							print_delayacct((struct taskstats *) NLA_DATA(na));

						if (print_io_accounting)

							print_ioacct((struct taskstats *) NLA_DATA(na));

						if (print_task_context_switch_counts)

							task_context_switch_counts((struct taskstats *) NLA_DATA(na));

						if (fd) {

							if (write(fd, NLA_DATA(na), na->nla_len) < 0) {

								err(1,"write error\n");

Documentation/accounting/taskstats-struct.txt

+6 −0
Original line number Diff line number Diff line
@@ -22,6 +22,8 @@ There are three different groups of fields in the struct taskstats: 
    /* Extended accounting fields end */

    Their values are collected if CONFIG_TASK_XACCT is set.



4) Per-task and per-thread context switch count statistics



Future extension should add fields to the end of the taskstats struct, and

should not change the relative position of each field within the struct.
@@ -158,4 +160,8 @@ struct taskstats { 


	/* Extended accounting fields end */



4) Per-task and per-thread statistics

	__u64	nvcsw;			/* Context voluntary switch counter */

	__u64	nivcsw;			/* Context involuntary switch counter */



}

fs/proc/array.c

+10 −0
Original line number Diff line number Diff line
@@ -289,6 +289,15 @@ static inline char *task_cap(struct task_struct *p, char *buffer) 
			    cap_t(p->cap_effective));

}



static inline char *task_context_switch_counts(struct task_struct *p,

						char *buffer)

{

	return buffer + sprintf(buffer, "voluntary_ctxt_switches:\t%lu\n"

			    "nonvoluntary_ctxt_switches:\t%lu\n",

			    p->nvcsw,

			    p->nivcsw);

}



int proc_pid_status(struct task_struct *task, char * buffer)

{

	char * orig = buffer;
@@ -307,6 +316,7 @@ int proc_pid_status(struct task_struct *task, char * buffer) 
#if defined(CONFIG_S390)

	buffer = task_show_regs(task, buffer);

#endif

	buffer = task_context_switch_counts(task, buffer);

	return buffer - orig;

}

include/linux/taskstats.h

+4 −1
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ 
 */





#define TASKSTATS_VERSION	4

#define TASKSTATS_VERSION	5

#define TS_COMM_LEN		32	/* should be >= TASK_COMM_LEN

					 * in linux/sched.h */
@@ -149,6 +149,9 @@ struct taskstats { 
	__u64	read_bytes;		/* bytes of read I/O */

	__u64	write_bytes;		/* bytes of write I/O */

	__u64	cancelled_write_bytes;	/* bytes of cancelled write I/O */



	__u64  nvcsw;			/* voluntary_ctxt_switches */

	__u64  nivcsw;			/* nonvoluntary_ctxt_switches */

};

kernel/taskstats.c

+4 −0
Original line number Diff line number Diff line
@@ -196,6 +196,8 @@ static int fill_pid(pid_t pid, struct task_struct *tsk, 


	/* fill in basic acct fields */

	stats->version = TASKSTATS_VERSION;

	stats->nvcsw = tsk->nvcsw;

	stats->nivcsw = tsk->nivcsw;

	bacct_add_tsk(stats, tsk);



	/* fill in extended acct fields */
@@ -242,6 +244,8 @@ static int fill_tgid(pid_t tgid, struct task_struct *first, 
		 */

		delayacct_add_tsk(stats, tsk);



		stats->nvcsw += tsk->nvcsw;

		stats->nivcsw += tsk->nivcsw;

	} while_each_thread(first, tsk);



	unlock_task_sighand(first, &flags);