Re: [RFC PATCH 27/30] Code tagging based latency tracking

Steven Rostedt
2022-09-01T21:46:22Z

On Thu, 1 Sep 2022 17:38:44 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> # echo 'hist:keys=comm,prio,delta.buckets=10:sort=delta' > /sys/kernel/tracing/events/synthetic/wakeup_lat/trigger

The above could almost be done with sqlhist (but I haven't implemented
"buckets=10" yet because that's a new feature. But for now, let's do log2):

# sqlhist -e 'select comm,prio,cast(delta as log2) from wakeup_lat'

("-e" is to execute the command, as it normally only displays what commands
need to be run to create the synthetic events and histograms)

# cat /sys/kernel/tracing/events/synthetic/wakeup_lat/hist
# event histogram
#
# trigger info: hist:keys=comm,prio,delta.log2:vals=hitcount:sort=hitcount:size=2048 [active]
#

{ comm: migration/4 , prio: 0, delta: ~ 2^5 } hitcount: 1
{ comm: migration/0 , prio: 0, delta: ~ 2^4 } hitcount: 2
{ comm: rtkit-daemon , prio: 0, delta: ~ 2^7 } hitcount: 2
{ comm: rtkit-daemon , prio: 0, delta: ~ 2^6 } hitcount: 4
{ comm: migration/0 , prio: 0, delta: ~ 2^5 } hitcount: 8
{ comm: migration/4 , prio: 0, delta: ~ 2^4 } hitcount: 9
{ comm: migration/2 , prio: 0, delta: ~ 2^4 } hitcount: 10
{ comm: migration/5 , prio: 0, delta: ~ 2^4 } hitcount: 10
{ comm: migration/7 , prio: 0, delta: ~ 2^4 } hitcount: 10
{ comm: migration/1 , prio: 0, delta: ~ 2^4 } hitcount: 10
{ comm: migration/6 , prio: 0, delta: ~ 2^4 } hitcount: 10

Totals:
Hits: 76
Entries: 11
Dropped: 0

-- Steve