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| author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-02-12 18:21:03 +0100 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-03-03 23:33:43 +0100 |
| commit | b396bfdebffcc05a855137775e38f4652cbca454 (patch) | |
| tree | d46563923e44c99391b1066403a369e7b771ab00 /Documentation | |
| parent | Linux 5.6-rc4 (diff) | |
| download | linux-b396bfdebffcc05a855137775e38f4652cbca454.tar.xz linux-b396bfdebffcc05a855137775e38f4652cbca454.zip | |
tracing: Have hwlat ts be first instance and record count of instances
The hwlat tracer runs a loop of width time during a given window. It then
reports the max latency over a given threshold and records a timestamp. But
this timestamp is the time after the width has finished, and not the time it
actually triggered.
Record the actual time when the latency was greater than the threshold as
well as the number of times it was greater in a given width per window.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/trace/ftrace.rst | 32 |
1 files changed, 22 insertions, 10 deletions
diff --git a/Documentation/trace/ftrace.rst b/Documentation/trace/ftrace.rst index ff658e27d25b..99a0890e20ec 100644 --- a/Documentation/trace/ftrace.rst +++ b/Documentation/trace/ftrace.rst @@ -2126,6 +2126,8 @@ periodically make a CPU constantly busy with interrupts disabled. # cat trace # tracer: hwlat # + # entries-in-buffer/entries-written: 13/13 #P:8 + # # _-----=> irqs-off # / _----=> need-resched # | / _---=> hardirq/softirq @@ -2133,12 +2135,18 @@ periodically make a CPU constantly busy with interrupts disabled. # ||| / delay # TASK-PID CPU# |||| TIMESTAMP FUNCTION # | | | |||| | | - <...>-3638 [001] d... 19452.055471: #1 inner/outer(us): 12/14 ts:1499801089.066141940 - <...>-3638 [003] d... 19454.071354: #2 inner/outer(us): 11/9 ts:1499801091.082164365 - <...>-3638 [002] dn.. 19461.126852: #3 inner/outer(us): 12/9 ts:1499801098.138150062 - <...>-3638 [001] d... 19488.340960: #4 inner/outer(us): 8/12 ts:1499801125.354139633 - <...>-3638 [003] d... 19494.388553: #5 inner/outer(us): 8/12 ts:1499801131.402150961 - <...>-3638 [003] d... 19501.283419: #6 inner/outer(us): 0/12 ts:1499801138.297435289 nmi-total:4 nmi-count:1 + <...>-1729 [001] d... 678.473449: #1 inner/outer(us): 11/12 ts:1581527483.343962693 count:6 + <...>-1729 [004] d... 689.556542: #2 inner/outer(us): 16/9 ts:1581527494.889008092 count:1 + <...>-1729 [005] d... 714.756290: #3 inner/outer(us): 16/16 ts:1581527519.678961629 count:5 + <...>-1729 [001] d... 718.788247: #4 inner/outer(us): 9/17 ts:1581527523.889012713 count:1 + <...>-1729 [002] d... 719.796341: #5 inner/outer(us): 13/9 ts:1581527524.912872606 count:1 + <...>-1729 [006] d... 844.787091: #6 inner/outer(us): 9/12 ts:1581527649.889048502 count:2 + <...>-1729 [003] d... 849.827033: #7 inner/outer(us): 18/9 ts:1581527654.889013793 count:1 + <...>-1729 [007] d... 853.859002: #8 inner/outer(us): 9/12 ts:1581527658.889065736 count:1 + <...>-1729 [001] d... 855.874978: #9 inner/outer(us): 9/11 ts:1581527660.861991877 count:1 + <...>-1729 [001] d... 863.938932: #10 inner/outer(us): 9/11 ts:1581527668.970010500 count:1 nmi-total:7 nmi-count:1 + <...>-1729 [007] d... 878.050780: #11 inner/outer(us): 9/12 ts:1581527683.385002600 count:1 nmi-total:5 nmi-count:1 + <...>-1729 [007] d... 886.114702: #12 inner/outer(us): 9/12 ts:1581527691.385001600 count:1 The above output is somewhat the same in the header. All events will have @@ -2148,7 +2156,7 @@ interrupts disabled 'd'. Under the FUNCTION title there is: This is the count of events recorded that were greater than the tracing_threshold (See below). - inner/outer(us): 12/14 + inner/outer(us): 11/11 This shows two numbers as "inner latency" and "outer latency". The test runs in a loop checking a timestamp twice. The latency detected within @@ -2156,11 +2164,15 @@ interrupts disabled 'd'. Under the FUNCTION title there is: after the previous timestamp and the next timestamp in the loop is the "outer latency". - ts:1499801089.066141940 + ts:1581527483.343962693 + + The absolute timestamp that the first latency was recorded in the window. + + count:6 - The absolute timestamp that the event happened. + The number of times a latency was detected during the window. - nmi-total:4 nmi-count:1 + nmi-total:7 nmi-count:1 On architectures that support it, if an NMI comes in during the test, the time spent in NMI is reported in "nmi-total" (in |