* [PATCH] perf sched: Rename switches to count and add usage description, options for latency
@ 2024-03-28 9:00 Madadi Vineeth Reddy
2024-04-15 2:31 ` Madadi Vineeth Reddy
2024-05-09 9:19 ` Aditya Gupta
0 siblings, 2 replies; 4+ messages in thread
From: Madadi Vineeth Reddy @ 2024-03-28 9:00 UTC (permalink / raw
To: peterz, mingo, acme, namhyung, mark.rutland, alexander.shishkin,
jolsa, irogers, adrian.hunter, linux-perf-users, linux-kernel
Cc: vineethr
Rename 'Switches' to 'Count' and document metrics shown for perf
sched latency output. Also add options possible with perf sched
latency.
Initially, after seeing the output of 'perf sched latency', the term
'Switches' seemed like it's the number of context switches-in for a
particular task, but upon going through the code, it was observed that
it's actually keeping track of number of times a delay was calculated so
that it is used in calculation of the average delay.
Actually, the switches here is a subset of number of context switches-in
because there are some cases where the count is not incremented in
switch-in handler 'add_sched_in_event'. For example when a task is
switched-in while it's state is not ready to run(!= THREAD_WAIT_CPU).
commit d9340c1db3f5 ("perf sched: Display time in milliseconds, reorganize
output") changed it from the original count to switches.
So, renamed switches to count to make things a bit more clearer and
added the metrics description of latency in the document.
Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
---
tools/perf/Documentation/perf-sched.txt | 36 +++++++++++++++++++++++++
tools/perf/builtin-sched.c | 2 +-
2 files changed, 37 insertions(+), 1 deletion(-)
diff --git a/tools/perf/Documentation/perf-sched.txt b/tools/perf/Documentation/perf-sched.txt
index 5fbe42bd599b..a216d2991b19 100644
--- a/tools/perf/Documentation/perf-sched.txt
+++ b/tools/perf/Documentation/perf-sched.txt
@@ -20,6 +20,26 @@ There are several variants of 'perf sched':
'perf sched latency' to report the per task scheduling latencies
and other scheduling properties of the workload.
+ Example usage:
+ perf sched record -- sleep 1
+ perf sched latency
+
+ -------------------------------------------------------------------------------------------------------------------------------------------
+ Task | Runtime ms | Count | Avg delay ms | Max delay ms | Max delay start | Max delay end |
+ -------------------------------------------------------------------------------------------------------------------------------------------
+ perf:(2) | 2.804 ms | 66 | avg: 0.524 ms | max: 1.069 ms | max start: 254752.314960 s | max end: 254752.316029 s
+ NetworkManager:1343 | 0.372 ms | 13 | avg: 0.008 ms | max: 0.013 ms | max start: 254751.551153 s | max end: 254751.551166 s
+ kworker/1:2-xfs:4649 | 0.012 ms | 1 | avg: 0.008 ms | max: 0.008 ms | max start: 254751.519807 s | max end: 254751.519815 s
+ kworker/3:1-xfs:388 | 0.011 ms | 1 | avg: 0.006 ms | max: 0.006 ms | max start: 254751.519809 s | max end: 254751.519815 s
+ sleep:147736 | 0.938 ms | 3 | avg: 0.006 ms | max: 0.007 ms | max start: 254751.313817 s | max end: 254751.313824 s
+
+ It shows Runtime(time that a task spent actually running on the CPU),
+ Count(number of times a delay was calculated) and delay(time that a
+ task was ready to run but was kept waiting).
+
+ Tasks with the same command name are merged and the merge count is
+ given within (), However if -p option is used, pid is mentioned.
+
'perf sched script' to see a detailed trace of the workload that
was recorded (aliased to 'perf script' for now).
@@ -78,6 +98,22 @@ OPTIONS
--force::
Don't complain, do it.
+OPTIONS for 'perf sched latency'
+-------------------------------
+
+-C::
+--CPU <n>::
+ CPU to profile on.
+
+-p::
+--pids::
+ latency stats per pid instead of per command name.
+
+-s::
+--sort <key[,key2...]>::
+ sort by key(s): runtime, switch, avg, max
+ by default it's sorted by "avg ,max ,switch ,runtime".
+
OPTIONS for 'perf sched map'
----------------------------
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index b248c433529a..e66a935eab6f 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -3210,7 +3210,7 @@ static int perf_sched__lat(struct perf_sched *sched)
perf_sched__sort_lat(sched);
printf("\n -------------------------------------------------------------------------------------------------------------------------------------------\n");
- printf(" Task | Runtime ms | Switches | Avg delay ms | Max delay ms | Max delay start | Max delay end |\n");
+ printf(" Task | Runtime ms | Count | Avg delay ms | Max delay ms | Max delay start | Max delay end |\n");
printf(" -------------------------------------------------------------------------------------------------------------------------------------------\n");
next = rb_first_cached(&sched->sorted_atom_root);
--
2.39.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] perf sched: Rename switches to count and add usage description, options for latency
2024-03-28 9:00 [PATCH] perf sched: Rename switches to count and add usage description, options for latency Madadi Vineeth Reddy
@ 2024-04-15 2:31 ` Madadi Vineeth Reddy
2024-05-09 9:19 ` Aditya Gupta
1 sibling, 0 replies; 4+ messages in thread
From: Madadi Vineeth Reddy @ 2024-04-15 2:31 UTC (permalink / raw
To: peterz, mingo, acme, namhyung, mark.rutland, alexander.shishkin,
jolsa, irogers, adrian.hunter, acme, linux-perf-users,
linux-kernel
Cc: Madadi Vineeth Reddy
On 28/03/24 14:30, Madadi Vineeth Reddy wrote:
> Rename 'Switches' to 'Count' and document metrics shown for perf
> sched latency output. Also add options possible with perf sched
> latency.
>
> Initially, after seeing the output of 'perf sched latency', the term
> 'Switches' seemed like it's the number of context switches-in for a
> particular task, but upon going through the code, it was observed that
> it's actually keeping track of number of times a delay was calculated so
> that it is used in calculation of the average delay.
>
> Actually, the switches here is a subset of number of context switches-in
> because there are some cases where the count is not incremented in
> switch-in handler 'add_sched_in_event'. For example when a task is
> switched-in while it's state is not ready to run(!= THREAD_WAIT_CPU).
>
> commit d9340c1db3f5 ("perf sched: Display time in milliseconds, reorganize
> output") changed it from the original count to switches.
>
> So, renamed switches to count to make things a bit more clearer and
> added the metrics description of latency in the document.
>
> Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
> ---
Hi Arnaldo,
Any comments on this patch?
Thanks and Regards
Madadi Vineeth Reddy
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] perf sched: Rename switches to count and add usage description, options for latency
2024-03-28 9:00 [PATCH] perf sched: Rename switches to count and add usage description, options for latency Madadi Vineeth Reddy
2024-04-15 2:31 ` Madadi Vineeth Reddy
@ 2024-05-09 9:19 ` Aditya Gupta
2024-05-10 14:11 ` Arnaldo Carvalho de Melo
1 sibling, 1 reply; 4+ messages in thread
From: Aditya Gupta @ 2024-05-09 9:19 UTC (permalink / raw
To: Madadi Vineeth Reddy
Cc: peterz, mingo, acme, namhyung, mark.rutland, alexander.shishkin,
jolsa, irogers, adrian.hunter, linux-perf-users, linux-kernel
Hello vineeth,
On Thu, Mar 28, 2024 at 02:30:05PM +0530, Madadi Vineeth Reddy wrote:
> Rename 'Switches' to 'Count' and document metrics shown for perf
> sched latency output. Also add options possible with perf sched
> latency.
>
> Initially, after seeing the output of 'perf sched latency', the term
> 'Switches' seemed like it's the number of context switches-in for a
> particular task, but upon going through the code, it was observed that
> it's actually keeping track of number of times a delay was calculated so
> that it is used in calculation of the average delay.
>
> Actually, the switches here is a subset of number of context switches-in
> because there are some cases where the count is not incremented in
> switch-in handler 'add_sched_in_event'. For example when a task is
> switched-in while it's state is not ready to run(!= THREAD_WAIT_CPU).
>
> commit d9340c1db3f5 ("perf sched: Display time in milliseconds, reorganize
> output") changed it from the original count to switches.
>
> So, renamed switches to count to make things a bit more clearer and
> added the metrics description of latency in the document.
>
> Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Makes sense to me. 'Switches' seems to be context switches, so it might
be better kept as 'Count' only.
Hence,
Reviewed-by: Aditya Gupta <adityag@linux.ibm.com>
Thanks,
Aditya Gupta
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] perf sched: Rename switches to count and add usage description, options for latency
2024-05-09 9:19 ` Aditya Gupta
@ 2024-05-10 14:11 ` Arnaldo Carvalho de Melo
0 siblings, 0 replies; 4+ messages in thread
From: Arnaldo Carvalho de Melo @ 2024-05-10 14:11 UTC (permalink / raw
To: Aditya Gupta
Cc: Madadi Vineeth Reddy, peterz, mingo, namhyung, mark.rutland,
alexander.shishkin, jolsa, irogers, adrian.hunter,
linux-perf-users, linux-kernel
On Thu, May 09, 2024 at 02:49:56PM +0530, Aditya Gupta wrote:
> Hello vineeth,
>
> On Thu, Mar 28, 2024 at 02:30:05PM +0530, Madadi Vineeth Reddy wrote:
> > Rename 'Switches' to 'Count' and document metrics shown for perf
> > sched latency output. Also add options possible with perf sched
> > latency.
> >
> > Initially, after seeing the output of 'perf sched latency', the term
> > 'Switches' seemed like it's the number of context switches-in for a
> > particular task, but upon going through the code, it was observed that
> > it's actually keeping track of number of times a delay was calculated so
> > that it is used in calculation of the average delay.
> >
> > Actually, the switches here is a subset of number of context switches-in
> > because there are some cases where the count is not incremented in
> > switch-in handler 'add_sched_in_event'. For example when a task is
> > switched-in while it's state is not ready to run(!= THREAD_WAIT_CPU).
> >
> > commit d9340c1db3f5 ("perf sched: Display time in milliseconds, reorganize
> > output") changed it from the original count to switches.
> >
> > So, renamed switches to count to make things a bit more clearer and
> > added the metrics description of latency in the document.
> >
> > Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
>
> Makes sense to me. 'Switches' seems to be context switches, so it might
> be better kept as 'Count' only.
>
> Hence,
>
> Reviewed-by: Aditya Gupta <adityag@linux.ibm.com>
Thanks, applied to perf-tools-next,
- Arnaldo
- Arnaldo
^ permalink raw reply [flat|nested] 4+ messages in thread
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2024-03-28 9:00 [PATCH] perf sched: Rename switches to count and add usage description, options for latency Madadi Vineeth Reddy
2024-04-15 2:31 ` Madadi Vineeth Reddy
2024-05-09 9:19 ` Aditya Gupta
2024-05-10 14:11 ` Arnaldo Carvalho de Melo
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