3:37 p.m.
Sometimes kernel image is generated without CONFIG_SCHEDSTATS or CONFIG_SCHED_INFO.
Where relevant commit id is f6db83479932 ("sched/stat: Simplify the sched_info
accounting")
- CONFIG_SCHED_INFO: KERNEL_VERSION >= LINUX(4,2,0)
- CONFIG_SCHEDSTATS: KERNEL_VERSION < LINUX(4,2,0)
Running crash-utility with above kernel image,
"ps -l" option cannot display all processes sorted with most recently-run
process.
Also "ps -m" option cannot display all processes with timestamp.
crash> ps -l or crash> ps -m
ps: last-run timestamps do not exist in this kernel
Usage: ps [-k|-u|-G] [-s]
[-p|-c|-t|-[l|m][-C cpu]|-a|-g|-r|-S]
[pid | task | command] ...
Enter "help ps" for details.
This is because output of "ps -l|-m" depends on
task_struct.sched_info.last_arrival.
Without CONFIG_SCHEDSTATS or CONFIG_SCHED_INFO, 'sched_info' field is not
included
in task_struct. In this case we make "ps -l|-m" option to access
'exec_start'
field of sched_entity where 'exec_start' is task_struct.se.exec_start.
The 'task_struct.se.exec_start' contains the most recently-executed timestamp
when process is running in the below cases;
- enqueued to runqueue
- dequeued from runqueue
- scheduler tick is invoked
- etc
'task_struct.se.exec_start' could be one of statistics which indicates the most
recently-run timestamp of process activity.
With this patch, "ps -l|-m" option works well without CONFIG_SCHEDSTATS or
CONFIG_SCHED_INFO.
Signed-off-by: Austin Kim <austindh.kim(a)gmail.com>
---
defs.h | 1 +
help.c | 5 +++--
symbols.c | 2 ++
task.c | 20 ++++++++++++++++----
4 files changed, 22 insertions(+), 6 deletions(-)
diff --git a/defs.h b/defs.h
index bf2c59b..841bd0b 100644
--- a/defs.h
+++ b/defs.h
@@ -2168,6 +2168,7 @@ struct offset_table { /* stash of commonly-used
offsets */
long sbitmap_queue_min_shallow_depth;
long sbq_wait_state_wait_cnt;
long sbq_wait_state_wait;
+ long sched_entity_exec_start;
};
struct size_table { /* stash of commonly-used sizes */
diff --git a/help.c b/help.c
index 8347668..6ca7c92 100644
--- a/help.c
+++ b/help.c
@@ -1442,7 +1442,8 @@ char *help_ps[] = {
" and system times.",
" -l display the task's last-run timestamp value, using either
the",
" task_struct's last_run value, the task_struct's timestamp
value",
-" or the task_struct's sched_entity last_arrival value,
whichever",
+" the task_struct's sched_info last_arrival value",
+" or the task_struct's sched_entity exec_start value,
whichever",
" applies, of selected, or all, tasks; the list is sorted with the",
" most recently-run task (with the largest timestamp) shown first,",
" followed by the task's current state.",
@@ -1621,7 +1622,7 @@ char *help_ps[] = {
" > 9497 1 0 ffff880549ec2ab0 RU 0.0 42314692 138664
oracle",
" ",
" Show all tasks sorted by their task_struct's last_run, timestamp, or",
-" sched_entity last_arrival timestamp value, whichever applies:\n",
+" sched_info last_arrival or sched_entity exec_start timestamp value, whichever
applies:\n",
" %s> ps -l",
" [20811245123] [IN] PID: 37 TASK: f7153030 CPU: 2 COMMAND:
\"events/2\"",
" [20811229959] [IN] PID: 1756 TASK: f2a5a570 CPU: 2 COMMAND:
\"ntpd\"",
diff --git a/symbols.c b/symbols.c
index ba5e274..1c40586 100644
--- a/symbols.c
+++ b/symbols.c
@@ -10290,6 +10290,8 @@ dump_offset_table(char *spec, ulong makestruct)
OFFSET(sched_entity_my_q));
fprintf(fp, " sched_entity_on_rq: %ld\n",
OFFSET(sched_entity_on_rq));
+ fprintf(fp, " sched_entity_exec_start: %ld\n",
+ OFFSET(sched_entity_exec_start));
fprintf(fp, " cfs_rq_nr_running: %ld\n",
OFFSET(cfs_rq_nr_running));
fprintf(fp, " cfs_rq_rb_leftmost: %ld\n",
diff --git a/task.c b/task.c
index 864c838..2c12196 100644
--- a/task.c
+++ b/task.c
@@ -334,9 +334,15 @@ task_init(void)
if (VALID_MEMBER(task_struct_sched_info))
MEMBER_OFFSET_INIT(sched_info_last_arrival,
"sched_info", "last_arrival");
+ MEMBER_OFFSET_INIT(task_struct_se, "task_struct", "se");
+ if (VALID_MEMBER(task_struct_se)) {
+ STRUCT_SIZE_INIT(sched_entity, "sched_entity");
+ MEMBER_OFFSET_INIT(sched_entity_exec_start, "sched_entity",
"exec_start");
+ }
if (VALID_MEMBER(task_struct_last_run) ||
VALID_MEMBER(task_struct_timestamp) ||
- VALID_MEMBER(sched_info_last_arrival)) {
+ VALID_MEMBER(sched_info_last_arrival) ||
+ VALID_MEMBER(sched_entity_exec_start)) {
char buf[BUFSIZE];
strcpy(buf, "alias last ps -l");
alias_init(buf);
@@ -3559,7 +3565,8 @@ cmd_ps(void)
case 'm':
if (INVALID_MEMBER(task_struct_last_run) &&
INVALID_MEMBER(task_struct_timestamp) &&
- INVALID_MEMBER(sched_info_last_arrival)) {
+ INVALID_MEMBER(sched_info_last_arrival) &&
+ INVALID_MEMBER(sched_entity_exec_start)) {
error(INFO,
"last-run timestamps do not exist in this
kernel\n");
argerrs++;
@@ -3574,7 +3581,8 @@ cmd_ps(void)
case 'l':
if (INVALID_MEMBER(task_struct_last_run) &&
INVALID_MEMBER(task_struct_timestamp) &&
- INVALID_MEMBER(sched_info_last_arrival)) {
+ INVALID_MEMBER(sched_info_last_arrival) &&
+ INVALID_MEMBER(sched_entity_exec_start)) {
error(INFO,
"last-run timestamps do not exist in this
kernel\n");
argerrs++;
@@ -6020,7 +6028,11 @@ task_last_run(ulong task)
timestamp = tt->last_task_read ? ULONGLONG(tt->task_struct +
OFFSET(task_struct_sched_info) +
OFFSET(sched_info_last_arrival)) : 0;
-
+ else if (VALID_MEMBER(sched_entity_exec_start))
+ timestamp = tt->last_task_read ? ULONGLONG(tt->task_struct +
+ OFFSET(task_struct_se) +
+ OFFSET(sched_entity_exec_start)) : 0;
+
return timestamp;
}
--
2.20.1