Re: [PATCH] Performance Stats: Kernel patch

[Andrew Morton]

On Tue, 05 Jun 2007 14:43:50 +0000 Maxim Uvarov <muvarov@xxxxxxxxxxxxx> wrote:

> Patch makes 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.
> Signed-off-by: Maxim Uvarov <muvarov@xxxxxxxxxxxxx>

Thanks.

Please retain suitable cc's when discussing a patch.  I keep on having to
find your updates on the mailing list, and then adding all the same cc's
when I reply.

Your patch seemed to be against some horridly prehistoric kernel, so I had
a few things to fix up.

I disagree with the term "rates" for these things.  They are counters, not
rates.  Adjustments are below.

We still need to think about whether we missed any other fields.


diff -puN Documentation/accounting/getdelays.c~taskstats-add-context-switch-counters-fix Documentation/accounting/getdelays.c
--- a/Documentation/accounting/getdelays.c~taskstats-add-context-switch-counters-fix
+++ a/Documentation/accounting/getdelays.c
@@ -49,7 +49,7 @@ char name[100];
 int dbg;
 int print_delays;
 int print_io_accounting;
-int print_task_context_switch_rates;
+int print_task_context_switch_counts;
 __u64 stime, utime;
 
 #define PRINTF(fmt, arg...) {			\
@@ -205,7 +205,7 @@ void print_delayacct(struct taskstats *t
 	       "count", "delay total", t->swapin_count, t->swapin_delay_total);
 }
 
-void task_context_switch_rates(struct taskstats *t)
+void task_context_switch_counts(struct taskstats *t)
 {
 	printf("\n\nTask   %15s%15s\n"
 	       "       %15lu%15lu\n",
@@ -259,7 +259,7 @@ int main(int argc, char *argv[])
 			break;
 		case 'q':
 			printf("printing task/process context switch rates\n");
-			print_task_context_switch_rates = 1;
+			print_task_context_switch_counts = 1;
 			break;
 		case 'w':
 			logfile = strdup(optarg);
@@ -402,8 +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_rates)
-							task_context_switch_rates((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 -puN Documentation/accounting/taskstats-struct.txt~taskstats-add-context-switch-counters-fix Documentation/accounting/taskstats-struct.txt
--- a/Documentation/accounting/taskstats-struct.txt~taskstats-add-context-switch-counters-fix
+++ a/Documentation/accounting/taskstats-struct.txt
@@ -22,7 +22,7 @@ There are three different groups of fiel
     /* Extended accounting fields end */
     Their values are collected if CONFIG_TASK_XACCT is set.
 
-4) Per-task and per-thread context switch rates statistics
+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.
diff -puN fs/proc/array.c~taskstats-add-context-switch-counters-fix fs/proc/array.c
--- a/fs/proc/array.c~taskstats-add-context-switch-counters-fix
+++ a/fs/proc/array.c
@@ -290,7 +290,9 @@ static inline char *task_cap(struct task
 			    cap_t(p->cap_permitted),
 			    cap_t(p->cap_effective));
 }
-static inline char *task_context_switch_rates(struct task_struct *p, char *buffer)
+
+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",
@@ -316,7 +318,7 @@ int proc_pid_status(struct task_struct *
 #if defined(CONFIG_S390)
 	buffer = task_show_regs(task, buffer);
 #endif
-	buffer = task_context_switch_rates(task, buffer);
+	buffer = task_context_switch_counts(task, buffer);
 	return buffer - orig;
 }
 
_

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