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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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bf10e6ee2a
While 'perf sched latency' reports task runtime and delay statistics
(average and maximum delay), it does not provide a visual representation
of how task wait times are distributed across latency ranges between
snapshots (start and finish of the analysis window).
The --histogram option collects CPU wait latencies (time between when
a task becomes runnable and when it gets scheduled onto a CPU) into 22
latency buckets, displaying an ASCII bar chart distribution.
The --hist-mode option configures the bucketing scheme:
- log (default). Logarithmic latency buckets ranging from
sub-microsecond (< 1 us) up to >= 1.05 seconds
- linear. Equal-width linear latency buckets
(i.e., 100 us steps up to >= 2.1 ms)
The --time option allows filtering trace event processing to a
specific time interval [start,stop].
Example histogram output excerpt:
❯ sudo perf sched latency --histogram --CPU 0
CPU Wait Latency Distribution Histogram (between snapshots) (total samples: 36114)
-------------------------------------------------------------------
Latency Range | Count | Pct | Histogram Graph
-------------------------------------------------------------------
< 1 us | 17 | 0.0% | #
2 - 4 us | 673 | 1.9% | #
4 - 8 us | 6237 | 17.3% | ######
8 - 16 us | 3224 | 8.9% | ###
16 - 32 us | 1388 | 3.8% | #
32 - 64 us | 709 | 2.0% | #
64 - 128 us | 690 | 1.9% | #
128 - 256 us | 789 | 2.2% | #
256 - 512 us | 541 | 1.5% | #
512 - 1024 us | 2256 | 6.2% | ##
1 - 2 ms | 3577 | 9.9% | ###
2 - 4 ms | 13259 | 36.7% | ##############
4 - 8 ms | 2523 | 7.0% | ##
8 - 16 ms | 222 | 0.6% | #
16 - 32 ms | 10 | 0.0% | #
>= 1.05 s | 3 | 0.0% | #
-------------------------------------------------------------------
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Aaron Tomlin <atomlin@atomlin.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
146 lines
2.7 KiB
Bash
Executable File
146 lines
2.7 KiB
Bash
Executable File
#!/bin/bash
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# perf sched tests
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# SPDX-License-Identifier: GPL-2.0
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set -e
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if [ "$(id -u)" != 0 ]; then
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echo "[Skip] No root permission"
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exit 2
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fi
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err=0
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perfdata=$(mktemp /tmp/__perf_test_sched.perf.data.XXXXX)
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PID1=0
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PID2=0
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cleanup() {
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rm -f "${perfdata}"
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rm -f "${perfdata}".old
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trap - EXIT TERM INT
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}
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trap_cleanup() {
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echo "Unexpected signal in ${FUNCNAME[1]}"
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cleanup
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exit 1
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}
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trap trap_cleanup EXIT TERM INT
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start_noploops() {
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# Start two noploop workloads on CPU0 to trigger scheduling.
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perf test -w noploop 10 &
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PID1=$!
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taskset -pc 0 $PID1
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perf test -w noploop 10 &
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PID2=$!
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taskset -pc 0 $PID2
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if ! grep -q 'Cpus_allowed_list:\s*0$' "/proc/$PID1/status"
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then
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echo "Sched [Error taskset did not work for the 1st noploop ($PID1)]"
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grep Cpus_allowed /proc/$PID1/status
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err=1
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fi
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if ! grep -q 'Cpus_allowed_list:\s*0$' "/proc/$PID2/status"
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then
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echo "Sched [Error taskset did not work for the 2nd noploop ($PID2)]"
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grep Cpus_allowed /proc/$PID2/status
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err=1
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fi
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}
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cleanup_noploops() {
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kill "$PID1" "$PID2" || true
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}
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test_sched_record() {
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echo "Sched record"
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start_noploops
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perf sched record --no-inherit -o "${perfdata}" sleep 1
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cleanup_noploops
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}
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test_sched_latency() {
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echo "Sched latency"
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if ! perf sched latency -i "${perfdata}" | grep -q perf-noploop
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then
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echo "Sched latency [Failed missing output]"
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err=1
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fi
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}
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test_sched_latency_histogram() {
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echo "Sched latency histogram"
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if ! perf sched latency -H -i "${perfdata}" | grep -q "Latency Distribution Histogram"
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then
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echo "Sched latency histogram [Failed missing log histogram]"
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err=1
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fi
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if ! perf sched latency --histogram --hist-mode linear -i "${perfdata}" | grep -q "Latency Distribution Histogram"
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then
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echo "Sched latency histogram [Failed missing linear histogram]"
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err=1
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fi
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}
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test_sched_latency_time() {
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echo "Sched latency time filter"
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if ! perf sched latency --time 0, -i "${perfdata}" | grep -q perf-noploop
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then
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echo "Sched latency time filter [Failed missing output]"
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err=1
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fi
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}
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test_sched_script() {
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echo "Sched script"
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if ! perf sched script -i "${perfdata}" | grep -q perf-noploop
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then
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echo "Sched script [Failed missing output]"
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err=1
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fi
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}
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test_sched_map() {
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echo "Sched map"
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if ! perf sched map -i "${perfdata}" | grep -q perf-noploop
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then
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echo "Sched map [Failed missing output]"
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err=1
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fi
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}
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test_sched_timehist() {
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echo "Sched timehist"
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if ! perf sched timehist -i "${perfdata}" | grep -q perf-noploop
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then
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echo "Sched timehist [Failed missing output]"
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err=1
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fi
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}
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test_sched_record
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test_sched_latency
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test_sched_latency_histogram
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test_sched_latency_time
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test_sched_script
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test_sched_map
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test_sched_timehist
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cleanup
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exit $err
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