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: Maxim 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/accounting/getdelays.c b/Documentation/accounting/getdelays.c
index 71acc28..24c5aad 100644
--- a/Documentation/accounting/getdelays.c
+++ b/Documentation/accounting/getdelays.c
@@ -49,6 +49,7 @@
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 @@
"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 @@
"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 @@
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 @@
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 @@
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");
diff --git a/Documentation/accounting/taskstats-struct.txt b/Documentation/accounting/taskstats-struct.txt
index 661c797..8aa7529 100644
--- a/Documentation/accounting/taskstats-struct.txt
+++ b/Documentation/accounting/taskstats-struct.txt
@@ -22,6 +22,8 @@
/* 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 @@
/* Extended accounting fields end */
+4) Per-task and per-thread statistics
+ __u64 nvcsw; /* Context voluntary switch counter */
+ __u64 nivcsw; /* Context involuntary switch counter */
+
}
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 680c913..9cbab7e 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -289,6 +289,15 @@
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 @@
#if defined(CONFIG_S390)
buffer = task_show_regs(task, buffer);
#endif
+ buffer = task_context_switch_counts(task, buffer);
return buffer - orig;
}
diff --git a/include/linux/taskstats.h b/include/linux/taskstats.h
index a46104a..dce1ed204 100644
--- a/include/linux/taskstats.h
+++ b/include/linux/taskstats.h
@@ -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 @@
__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 */
};
diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index 906cae7..059431e 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -196,6 +196,8 @@
/* 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 @@
*/
delayacct_add_tsk(stats, tsk);
+ stats->nvcsw += tsk->nvcsw;
+ stats->nivcsw += tsk->nivcsw;
} while_each_thread(first, tsk);
unlock_task_sighand(first, &flags);
