linux/tools
Ian Rogers a8e4e88083 perf metric: Don't compute unused events
For a metric like:

  EVENT1 if #smt_on else EVENT2

currently EVENT1 and EVENT2 will be measured and then when the metric is
reported EVENT1 or EVENT2 will be printed depending on the value from
smt_on() during the expr parsing. Computing both events is unnecessary and
can lead to multiplexing as discussed in this thread:

  https://lore.kernel.org/lkml/20201110100346.2527031-1-irogers@google.com/

If the input is constant to certain operators like:

 IDS1 if CONST else IDS2

then the result will be either IDS1 or IDS2 depending on CONST (which
may be evaluated from an entire expression), and so IDS1 or IDS2 may
be discarded avoiding events from being programmed.

Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: John Garry <john.garry@huawei.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sandeep Dasgupta <sdasgup@google.com>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20210923074616.674826-13-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2021-09-29 13:51:04 -03:00
..
accounting
arch tools headers UAPI: Sync x86's asm/kvm.h with the kernel sources 2021-09-10 18:15:22 -03:00
bootconfig tools/bootconfig: Define memblock_free_ptr() to fix build error 2021-09-15 09:49:48 -07:00
bpf Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2021-07-31 11:23:26 -07:00
build perf tools: Enable libtracefs dynamic linking 2021-09-28 16:08:37 -03:00
cgroup
debugging tools: Fix "the the" in a message in kernel-chktaint 2021-06-13 17:01:17 -06:00
edid
firewire
firmware
gpio
hv
iio
include tools: compiler-gcc.h: Guard error attribute use with __has_attribute 2021-09-13 15:51:41 -07:00
io_uring tools/io_uring/io_uring-cp: sync with liburing example 2021-08-13 08:58:11 -06:00
kvm/kvm_stat
laptop
leds
lib libperf evsel: Make use of FD robust. 2021-09-18 17:43:06 -03:00
memory-model tools/memory-model: Document data_race(READ_ONCE()) 2021-07-27 11:48:55 -07:00
objtool A single ELF format fix for a section flags mismatch bug that breaks 2021-06-28 11:35:55 -07:00
pci tools: PCI: Zero-initialize param 2021-08-05 11:01:30 +01:00
pcmcia
perf perf metric: Don't compute unused events 2021-09-29 13:51:04 -03:00
power tools/power/x86/intel-speed-select: v1.10 release 2021-06-18 15:29:32 +02:00
rcu
scripts tools build: Fix quiet cmd indentation 2021-05-17 12:10:03 +09:00
spi
testing powerpc fixes for 5.15 #2 2021-09-19 13:00:23 -07:00
thermal/tmon tools/thermal/tmon: Add cross compiling support 2021-08-14 15:33:19 +02:00
time
tracing
usb
virtio tools/virtio: fix build 2021-08-11 06:44:24 -04:00
vm tools/vm/page_owner_sort.c: check malloc() return 2021-06-29 10:53:47 -07:00
wmi
Makefile