sieni
/
linux
mirror of git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
linux/tools/lib/perf
History
Adrian Hunter 6cc4479645 libperf evlist: Fix polling of system-wide events 
Originally, (refer commit f90d194a86 ("perf evlist: Do not poll
events that use the system_wide flag") there wasn't much reason to poll
system-wide events because:

 1. The mmaps get "merged" via set-output anyway (the per-cpu case)
 2. perf reads all mmaps when any event is woken
 3. system-wide mmaps do not fill up as fast as the mmaps for user
    selected events

But there was 1 reason not to poll which was that it prevented correct
termination due to POLLHUP on all user selected events.  That issue is
now easily resolved by using fdarray_flag__nonfilterable.

With the advent of commit ae4f8ae16a ("libperf evlist: Allow
mixing per-thread and per-cpu mmaps"), system-wide mmaps can be used
also in the per-thread case where reason 1 does not apply.

Fix the omission of system-wide events from polling by using the
fdarray_flag__nonfilterable flag.

Example:

 Before:

    $ perf record --no-bpf-event -vvv -e intel_pt// --per-thread uname 2>err.txt
    Linux
    $ grep 'sys_perf_event_open.*=\|pollfd' err.txt
    sys_perf_event_open: pid 155076  cpu -1  group_fd -1  flags 0x8 = 5
    sys_perf_event_open: pid 155076  cpu -1  group_fd -1  flags 0x8 = 6
    sys_perf_event_open: pid -1  cpu 0  group_fd -1  flags 0x8 = 7
    sys_perf_event_open: pid -1  cpu 1  group_fd -1  flags 0x8 = 9
    sys_perf_event_open: pid -1  cpu 2  group_fd -1  flags 0x8 = 10
    sys_perf_event_open: pid -1  cpu 3  group_fd -1  flags 0x8 = 11
    sys_perf_event_open: pid -1  cpu 4  group_fd -1  flags 0x8 = 12
    sys_perf_event_open: pid -1  cpu 5  group_fd -1  flags 0x8 = 13
    sys_perf_event_open: pid -1  cpu 6  group_fd -1  flags 0x8 = 14
    sys_perf_event_open: pid -1  cpu 7  group_fd -1  flags 0x8 = 15
    thread_data[0x55fb43c29e80]: pollfd[0] <- event_fd=5
    thread_data[0x55fb43c29e80]: pollfd[1] <- event_fd=6
    thread_data[0x55fb43c29e80]: pollfd[2] <- non_perf_event fd=4

 After:

    $ perf record --no-bpf-event -vvv -e intel_pt// --per-thread uname 2>err.txt
    Linux
    $ grep 'sys_perf_event_open.*=\|pollfd' err.txt
    sys_perf_event_open: pid 156316  cpu -1  group_fd -1  flags 0x8 = 5
    sys_perf_event_open: pid 156316  cpu -1  group_fd -1  flags 0x8 = 6
    sys_perf_event_open: pid -1  cpu 0  group_fd -1  flags 0x8 = 7
    sys_perf_event_open: pid -1  cpu 1  group_fd -1  flags 0x8 = 9
    sys_perf_event_open: pid -1  cpu 2  group_fd -1  flags 0x8 = 10
    sys_perf_event_open: pid -1  cpu 3  group_fd -1  flags 0x8 = 11
    sys_perf_event_open: pid -1  cpu 4  group_fd -1  flags 0x8 = 12
    sys_perf_event_open: pid -1  cpu 5  group_fd -1  flags 0x8 = 13
    sys_perf_event_open: pid -1  cpu 6  group_fd -1  flags 0x8 = 14
    sys_perf_event_open: pid -1  cpu 7  group_fd -1  flags 0x8 = 15
    thread_data[0x55cc19e58e80]: pollfd[0] <- event_fd=5
    thread_data[0x55cc19e58e80]: pollfd[1] <- event_fd=6
    thread_data[0x55cc19e58e80]: pollfd[2] <- event_fd=7
    thread_data[0x55cc19e58e80]: pollfd[3] <- event_fd=9
    thread_data[0x55cc19e58e80]: pollfd[4] <- event_fd=10
    thread_data[0x55cc19e58e80]: pollfd[5] <- event_fd=11
    thread_data[0x55cc19e58e80]: pollfd[6] <- event_fd=12
    thread_data[0x55cc19e58e80]: pollfd[7] <- event_fd=13
    thread_data[0x55cc19e58e80]: pollfd[8] <- event_fd=14
    thread_data[0x55cc19e58e80]: pollfd[9] <- event_fd=15
    thread_data[0x55cc19e58e80]: pollfd[10] <- non_perf_event fd=4

Fixes: ae4f8ae16a ("libperf evlist: Allow mixing per-thread and per-cpu mmaps")
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220915122612.81738-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
 		2022-09-21 16:08:00 -03:00
..
Documentation libperf: Add API for allocating new thread map array 2022-02-23 14:40:23 -03:00
include libperf: Handle read format in perf_evsel__read() 2022-08-19 15:56:27 -03:00
tests libperf: Add a test case for read formats 2022-08-19 15:56:44 -03:00
Build libperf: Change tests to single static and shared binaries 2021-07-07 11:41:58 -03:00
Makefile kbuild: replace $(if A,A,B) with $(or A,B) 2022-02-15 12:25:56 +09:00
core.c libperf: Move to tools/lib/perf 2020-01-06 11:46:09 -03:00
cpumap.c perf cpumap: Const map for max() 2022-08-19 12:26:58 -03:00
evlist.c libperf evlist: Fix polling of system-wide events 2022-09-21 16:08:00 -03:00
evsel.c libperf: Handle read format in perf_evsel__read() 2022-08-19 15:56:27 -03:00
internal.h libperf: Move to tools/lib/perf 2020-01-06 11:46:09 -03:00
lib.c libperf: Add preadn() 2022-05-23 10:11:12 -03:00
libperf.map libperf: Add API for allocating new thread map array 2022-02-23 14:40:23 -03:00
libperf.pc.template libperf: Move to tools/lib/perf 2020-01-06 11:46:09 -03:00
mmap.c libperf: Add arm64 support to perf_mmap__read_self() 2022-02-06 09:14:27 -03:00
threadmap.c libperf: Add API for allocating new thread map array 2022-02-23 14:40:23 -03:00
xyarray.c libperf: Move to tools/lib/perf 2020-01-06 11:46:09 -03:00