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| author |   Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-11-30 23:37:33 -0500 |
|---|---|---|
| committer | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2020-12-01 22:00:46 -0500 |
| commit | 5b7be9c709e10e88531f1f81e1150bbad65be1aa (patch) | |
| tree | 4be74dad91a33c16ce5ba077603fe54371354891 /kernel/trace/Kconfig | |
| parent | ftrace/documentation: Fix RST C code blocks (diff) | |
| download | linux-dev-5b7be9c709e10e88531f1f81e1150bbad65be1aa.tar.xz linux-dev-5b7be9c709e10e88531f1f81e1150bbad65be1aa.zip | |
ring-buffer: Add test to validate the time stamp deltas
While debugging a situation where a delta for an event was calucalted wrong,
I realize there was nothing making sure that the delta of events are
correct. If a single event has an incorrect delta, then all events after it
will also have one. If the discrepency gets large enough, it could cause
the time stamps to go backwards when crossing sub buffers, that record a
full 64 bit time stamp, and the new deltas are added to that.
Add a way to validate the events at most events and when crossing a buffer
page. This will help make sure that the deltas are always correct. This test
will detect if they are ever corrupted.
The test adds a high overhead to the ring buffer recording, as it does the
audit for almost every event, and should only be used for testing the ring
buffer.
This will catch the bug that is fixed by commit 55ea4cf40380 ("ring-buffer:
Update write stamp with the correct ts"), which is not applied when this
commit is applied.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/Kconfig')
| -rw-r--r-- | kernel/trace/Kconfig | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index c9b64dea1216..fe60f9d7a0e6 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -845,6 +845,26 @@ config RING_BUFFER_STARTUP_TEST If unsure, say N +config RING_BUFFER_VALIDATE_TIME_DELTAS + bool "Verify ring buffer time stamp deltas" + depends on RING_BUFFER + help + This will audit the time stamps on the ring buffer sub + buffer to make sure that all the time deltas for the + events on a sub buffer matches the current time stamp. + This audit is performed for every event that is not + interrupted, or interrupting another event. A check + is also made when traversing sub buffers to make sure + that all the deltas on the previous sub buffer do not + add up to be greater than the current time stamp. + + NOTE: This adds significant overhead to recording of events, + and should only be used to test the logic of the ring buffer. + Do not use it on production systems. + + Only say Y if you understand what this does, and you + still want it enabled. Otherwise say N + config MMIOTRACE_TEST tristate "Test module for mmiotrace" depends on MMIOTRACE && m |