Re: [Crash-utility] [PATCH v3] ps: Add support to "ps -l|-m" to properly display process

On Thu, Mar 3, 2022 at 10:43 AM <crash-utility-request(a)redhat.com&gt; wrote: > Date: Wed, 2 Mar 2022 21:37:45 +0000 > From: Austin Kim <austindh.kim(a)gmail.com&gt; > To: k-hagio-ab(a)nec.com, lijiang(a)redhat.com, crash-utility(a)redhat.com > Cc: kernel-team(a)lge.com, mikeseohyungjin(a)gmail.com > Subject: [Crash-utility] [PATCH v3] ps: Add support to "ps -l|-m" to > properly display process > Message-ID: <20220302213745.GA868@raspberrypi> > Content-Type: text/plain; charset=us-ascii > > 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. > Thank you for the update, Austin. If the task is migraged,

the value of the 'task_struct.se.exec_start ' will be set to zero and may be updated in the next scheduling with the new time. In this case, does the patch still work well as expected? Thanks. Lianbo 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&gt; > --- > 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 >