Namhyung Kim 54af75ddf3 perf stat: Do not delay the workload with --delay ... [ Upstream commit c587e77e10 ] The -D/--delay option is to delay the measure after the program starts. But the current code goes to sleep before starting the program so the program is delayed too. This is not the intention, let's fix it. Before: $ time sudo ./perf stat -a -e cycles -D 3000 sleep 4 Events disabled Events enabled Performance counter stats for 'system wide': 4,326,949,337 cycles 4.007494118 seconds time elapsed real 0m7.474s user 0m0.356s sys 0m0.120s It ran the workload for 4 seconds and gave the 3 second delay. So it should skip the first 3 second and measure the last 1 second only. But as you can see, it delays 3 seconds and ran the workload after that for 4 seconds. So the total time (real) was 7 seconds. After: $ time sudo ./perf stat -a -e cycles -D 3000 sleep 4 Events disabled Events enabled Performance counter stats for 'system wide': 1,063,551,013 cycles 1.002769510 seconds time elapsed real 0m4.484s user 0m0.385s sys 0m0.086s The bug was introduced when it changed enablement of system-wide events with a command line workload. But it should've considered the initial delay case. The code was reworked since then (in bb8bc52e75) so I'm afraid it won't be applied cleanly. Fixes: d0a0a51149 ("perf stat: Fix forked applications enablement of counters") Reported-by: Kevin Nomura <nomurak@google.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Thomas Richter <tmricht@linux.ibm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sumanth Korikkar <sumanthk@linux.ibm.com> Link: https://lore.kernel.org/r/20221212230820.901382-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>		2022-12-31 13:32:45 +01:00
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accounting	…
arch	x86/cpu: Restore AMD's DE_CFG MSR after resume	2022-11-15 10:15:58 -08:00
bootconfig	…
bpf	bpftool: Fix memory leak in do_build_table_cb	2022-12-31 13:32:23 +01:00
build	perf bpf: Fix build with libbpf 0.7.0 by checking if bpf_program__set_insns() is available	2022-10-25 17:40:48 -03:00
certs	…
cgroup	…
counter	…
debugging	…
edid	…
firewire	…
firmware	…
gpio	…
hv	…
iio	tools: iio: iio_generic_buffer: Fix read size	2022-11-01 08:48:13 +00:00
include	bpf-for-netdev	2022-11-03 19:51:02 -07:00
io_uring	…
kvm/kvm_stat	tools/kvm_stat: update exit reasons for vmx/svm/aarch64/userspace	2022-11-09 12:26:52 -05:00
laptop	…
leds	…
lib	libbpf: Btf dedup identical struct test needs check for nested structs/arrays	2022-12-31 13:32:04 +01:00
memory-model	…
objtool	objtool, kcsan: Add volatile read/write instrumentation to whitelist	2022-12-31 13:31:48 +01:00
pci	…
pcmcia	…
perf	perf stat: Do not delay the workload with --delay	2022-12-31 13:32:45 +01:00
power	pm-graph v5.10	2022-10-25 17:46:15 +02:00
rcu	…
scripts	…
spi	…
testing	netfilter: conntrack: set icmpv6 redirects as RELATED	2022-12-31 13:32:19 +01:00
thermal	…
time	…
tracing	…
usb	…
verification	rv/dot2c: Make automaton definition static	2022-10-20 16:02:45 -04:00
virtio	…
vm	tools/vm/slabinfo-gnuplot: use "grep -E" instead of "egrep"	2022-11-30 14:49:41 -08:00
wmi	…
Makefile	…