x86 and arm64 can both support direct access of event counters in userspace. The access sequence is less than trivial and currently exists in perf test code (tools/perf/arch/x86/tests/rdpmc.c) with copies in projects such as PAPI and libpfm4. In order to support userspace access, an event must be mmapped first with perf_evsel__mmap(). Then subsequent calls to perf_evsel__read() will use the fast path (assuming the arch supports it). Committer notes: Added a '__maybe_unused' attribute to the read_perf_counter() argument to fix the build on arches other than x86_64 and arm. Committer testing: Building and running the libperf tests in verbose mode (V=1) now shows those "loop = N, count = N" extra lines, testing user space counter access. # make V=1 -C tools/lib/perf tests make: Entering directory '/home/acme/git/perf/tools/lib/perf' make -f /home/acme/git/perf/tools/build/Makefile.build dir=. obj=libperf make -C /home/acme/git/perf/tools/lib/api/ O= libapi.a make -f /home/acme/git/perf/tools/build/Makefile.build dir=./fd obj=libapi make -f /home/acme/git/perf/tools/build/Makefile.build dir=./fs obj=libapi make -C tests gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-cpumap-a test-cpumap.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-threadmap-a test-threadmap.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-evlist-a test-evlist.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -o test-evsel-a test-evsel.c ../libperf.a /home/acme/git/perf/tools/lib/api/libapi.a gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-cpumap-so test-cpumap.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-threadmap-so test-threadmap.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-evlist-so test-evlist.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf gcc -I/home/acme/git/perf/tools/lib/perf/include -I/home/acme/git/perf/tools/include -I/home/acme/git/perf/tools/lib -g -Wall -L.. -o test-evsel-so test-evsel.c /home/acme/git/perf/tools/lib/api/libapi.a -lperf make -C tests run running static: - running test-cpumap.c...OK - running test-threadmap.c...OK - running test-evlist.c...OK - running test-evsel.c... loop = 65536, count = 333926 loop = 131072, count = 655781 loop = 262144, count = 1311141 loop = 524288, count = 2630126 loop = 1048576, count = 5256955 loop = 65536, count = 524594 loop = 131072, count = 1058916 loop = 262144, count = 2097458 loop = 524288, count = 4205429 loop = 1048576, count = 8406606 OK running dynamic: - running test-cpumap.c...OK - running test-threadmap.c...OK - running test-evlist.c...OK - running test-evsel.c... loop = 65536, count = 328102 loop = 131072, count = 655782 loop = 262144, count = 1317494 loop = 524288, count = 2627851 loop = 1048576, count = 5255187 loop = 65536, count = 524601 loop = 131072, count = 1048923 loop = 262144, count = 2107917 loop = 524288, count = 4194606 loop = 1048576, count = 8409322 OK make: Leaving directory '/home/acme/git/perf/tools/lib/perf' # Signed-off-by: Rob Herring <robh@kernel.org> Acked-by: Jiri Olsa <jolsa@redhat.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Itaru Kitayama <itaru.kitayama@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Link: http://lore.kernel.org/lkml/20210414155412.3697605-4-robh@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
201 lines
4.6 KiB
C
201 lines
4.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <stdarg.h>
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#include <stdio.h>
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#include <linux/perf_event.h>
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#include <perf/cpumap.h>
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#include <perf/threadmap.h>
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#include <perf/evsel.h>
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#include <internal/tests.h>
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static int libperf_print(enum libperf_print_level level,
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const char *fmt, va_list ap)
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{
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return vfprintf(stderr, fmt, ap);
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}
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static int test_stat_cpu(void)
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{
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struct perf_cpu_map *cpus;
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struct perf_evsel *evsel;
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struct perf_event_attr attr = {
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.type = PERF_TYPE_SOFTWARE,
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.config = PERF_COUNT_SW_CPU_CLOCK,
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};
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int err, cpu, tmp;
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cpus = perf_cpu_map__new(NULL);
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__T("failed to create cpus", cpus);
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evsel = perf_evsel__new(&attr);
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__T("failed to create evsel", evsel);
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err = perf_evsel__open(evsel, cpus, NULL);
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__T("failed to open evsel", err == 0);
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perf_cpu_map__for_each_cpu(cpu, tmp, cpus) {
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struct perf_counts_values counts = { .val = 0 };
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perf_evsel__read(evsel, cpu, 0, &counts);
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__T("failed to read value for evsel", counts.val != 0);
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}
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perf_evsel__close(evsel);
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perf_evsel__delete(evsel);
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perf_cpu_map__put(cpus);
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return 0;
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}
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static int test_stat_thread(void)
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{
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struct perf_counts_values counts = { .val = 0 };
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struct perf_thread_map *threads;
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struct perf_evsel *evsel;
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struct perf_event_attr attr = {
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.type = PERF_TYPE_SOFTWARE,
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.config = PERF_COUNT_SW_TASK_CLOCK,
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};
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int err;
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threads = perf_thread_map__new_dummy();
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__T("failed to create threads", threads);
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perf_thread_map__set_pid(threads, 0, 0);
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evsel = perf_evsel__new(&attr);
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__T("failed to create evsel", evsel);
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err = perf_evsel__open(evsel, NULL, threads);
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__T("failed to open evsel", err == 0);
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perf_evsel__read(evsel, 0, 0, &counts);
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__T("failed to read value for evsel", counts.val != 0);
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perf_evsel__close(evsel);
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perf_evsel__delete(evsel);
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perf_thread_map__put(threads);
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return 0;
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}
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static int test_stat_thread_enable(void)
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{
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struct perf_counts_values counts = { .val = 0 };
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struct perf_thread_map *threads;
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struct perf_evsel *evsel;
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struct perf_event_attr attr = {
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.type = PERF_TYPE_SOFTWARE,
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.config = PERF_COUNT_SW_TASK_CLOCK,
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.disabled = 1,
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};
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int err;
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threads = perf_thread_map__new_dummy();
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__T("failed to create threads", threads);
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perf_thread_map__set_pid(threads, 0, 0);
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evsel = perf_evsel__new(&attr);
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__T("failed to create evsel", evsel);
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err = perf_evsel__open(evsel, NULL, threads);
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__T("failed to open evsel", err == 0);
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perf_evsel__read(evsel, 0, 0, &counts);
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__T("failed to read value for evsel", counts.val == 0);
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err = perf_evsel__enable(evsel);
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__T("failed to enable evsel", err == 0);
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perf_evsel__read(evsel, 0, 0, &counts);
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__T("failed to read value for evsel", counts.val != 0);
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err = perf_evsel__disable(evsel);
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__T("failed to enable evsel", err == 0);
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perf_evsel__close(evsel);
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perf_evsel__delete(evsel);
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perf_thread_map__put(threads);
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return 0;
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}
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static int test_stat_user_read(int event)
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{
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struct perf_counts_values counts = { .val = 0 };
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struct perf_thread_map *threads;
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struct perf_evsel *evsel;
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struct perf_event_mmap_page *pc;
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struct perf_event_attr attr = {
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.type = PERF_TYPE_HARDWARE,
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.config = event,
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};
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int err, i;
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threads = perf_thread_map__new_dummy();
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__T("failed to create threads", threads);
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perf_thread_map__set_pid(threads, 0, 0);
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evsel = perf_evsel__new(&attr);
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__T("failed to create evsel", evsel);
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err = perf_evsel__open(evsel, NULL, threads);
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__T("failed to open evsel", err == 0);
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err = perf_evsel__mmap(evsel, 0);
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__T("failed to mmap evsel", err == 0);
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pc = perf_evsel__mmap_base(evsel, 0, 0);
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#if defined(__i386__) || defined(__x86_64__)
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__T("userspace counter access not supported", pc->cap_user_rdpmc);
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__T("userspace counter access not enabled", pc->index);
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__T("userspace counter width not set", pc->pmc_width >= 32);
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#endif
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perf_evsel__read(evsel, 0, 0, &counts);
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__T("failed to read value for evsel", counts.val != 0);
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for (i = 0; i < 5; i++) {
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volatile int count = 0x10000 << i;
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__u64 start, end, last = 0;
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__T_VERBOSE("\tloop = %u, ", count);
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perf_evsel__read(evsel, 0, 0, &counts);
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start = counts.val;
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while (count--) ;
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perf_evsel__read(evsel, 0, 0, &counts);
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end = counts.val;
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__T("invalid counter data", (end - start) > last);
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last = end - start;
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__T_VERBOSE("count = %llu\n", end - start);
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}
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perf_evsel__munmap(evsel);
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perf_evsel__close(evsel);
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perf_evsel__delete(evsel);
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perf_thread_map__put(threads);
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return 0;
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}
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int main(int argc, char **argv)
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{
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__T_START;
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libperf_init(libperf_print);
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test_stat_cpu();
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test_stat_thread();
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test_stat_thread_enable();
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test_stat_user_read(PERF_COUNT_HW_INSTRUCTIONS);
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test_stat_user_read(PERF_COUNT_HW_CPU_CYCLES);
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__T_END;
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return tests_failed == 0 ? 0 : -1;
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}
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