[Crash-utility] [PATCH v3] ps: Add support to "ps -l|-m" to properly display process
lijiang
lijiang at redhat.com
Tue Mar 15 05:29:19 UTC 2022
On Tue, Mar 15, 2022 at 1:08 PM lijiang <lijiang at redhat.com> wrote:
> On Thu, Mar 3, 2022 at 10:43 AM <crash-utility-request at redhat.com> wrote:
>
>> Date: Wed, 2 Mar 2022 21:37:45 +0000
>> From: Austin Kim <austindh.kim at gmail.com>
>> To: k-hagio-ab at nec.com, lijiang at redhat.com, crash-utility at redhat.com
>> Cc: kernel-team at lge.com, mikeseohyungjin at gmail.com
>> Subject: [Crash-utility] [PATCH v3] ps: Add support to "ps -l|-m" to
>> properly display process
>> Message-ID: <20220302213745.GA868 at 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,
>
^^^^^^^^
Sorry, it's a typo, replace it with the "migrated". Thanks.
> 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 at 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
>>
>
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