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| author | Kent Overstreet <kent.overstreet@linux.dev> | 2022-08-29 12:26:26 -0400 |
|---|---|---|
| committer | Suren Baghdasaryan <surenb@google.com> | 2023-03-13 15:11:37 +0000 |
| commit | ae3193f1356d204ea620fe6f81bdd459b41215d3 (patch) | |
| tree | b42dbcb54c687e7566f9fb91f47175737b9c8cb9 /lib/Kconfig.debug | |
| parent | d2e62ecd4674540ae7b1badbc02d4b511f2b97ac (diff) | |
Code tagging based latency tracking
This adds the ability to easily instrument code for measuring latency.
To use, add the following to calls to your code, at the start and end of
the event you wish to measure:
code_tag_time_stats_start(start_time);
code_tag_time_stats_finish(start_time);
Stastistics will then show up in debugfs under
/sys/kernel/debug/time_stats, listed by file and line number.
Stastics measured include weighted averages of frequency, duration, max
duration, as well as quantiles.
This patch also instruments all calls to init_wait and finish_wait,
which includes all calls to wait_event. Example debugfs output:
fs/xfs/xfs_trans_ail.c:746 module:xfs func:xfs_ail_push_all_sync
count: 17
rate: 0/sec
frequency: 2 sec
avg duration: 10 us
max duration: 232 us
quantiles (ns): 128 128 128 128 128 128 128 128 128 128 128 128 128 128 128
lib/sbitmap.c:813 module:sbitmap func:sbitmap_finish_wait
count: 3
rate: 0/sec
frequency: 4 sec
avg duration: 4 sec
max duration: 4 sec
quantiles (ns): 0 4288669120 4288669120 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048 5360836048
net/core/datagram.c:122 module:datagram func:__skb_wait_for_more_packets
count: 10
rate: 1/sec
frequency: 859 ms
avg duration: 472 ms
max duration: 30 sec
quantiles (ns): 0 12279 12279 15669 15669 15669 15669 17217 17217 17217 17217 17217 17217 17217 17217
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Diffstat (limited to 'lib/Kconfig.debug')
| -rw-r--r-- | lib/Kconfig.debug | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index e76bfa58dd2d..37ade69ae2ae 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1781,6 +1781,14 @@ config DEBUG_CGROUP_REF Force cgroup css reference count functions to not be inlined so that they can be kprobed for debugging. +config CODETAG_TIME_STATS + bool "Code tagging based latency measuring" + depends on DEBUG_FS + select TIME_STATS + select CODE_TAGGING + help + Enabling this option makes latency statistics available in debugfs + source "kernel/trace/Kconfig" config PROVIDE_OHCI1394_DMA_INIT |