1 // SPDX-License-Identifier: GPL-2.0 2 #include <stdio.h> 3 #include "api/fs/fs.h" 4 #include "util/pmu.h" 5 #include "util/topdown.h" 6 #include "topdown.h" 7 #include "evsel.h" 8 9 /* Check whether there is a PMU which supports the perf metrics. */ 10 bool topdown_sys_has_perf_metrics(void) 11 { 12 static bool has_perf_metrics; 13 static bool cached; 14 struct perf_pmu *pmu; 15 16 if (cached) 17 return has_perf_metrics; 18 19 /* 20 * The perf metrics feature is a core PMU feature. 21 * The PERF_TYPE_RAW type is the type of a core PMU. 22 * The slots event is only available when the core PMU 23 * supports the perf metrics feature. 24 */ 25 pmu = perf_pmu__find_by_type(PERF_TYPE_RAW); 26 if (pmu && pmu_have_event(pmu->name, "slots")) 27 has_perf_metrics = true; 28 29 cached = true; 30 return has_perf_metrics; 31 } 32 33 /* 34 * Check whether we can use a group for top down. 35 * Without a group may get bad results due to multiplexing. 36 */ 37 bool arch_topdown_check_group(bool *warn) 38 { 39 int n; 40 41 if (sysctl__read_int("kernel/nmi_watchdog", &n) < 0) 42 return false; 43 if (n > 0) { 44 *warn = true; 45 return false; 46 } 47 return true; 48 } 49 50 void arch_topdown_group_warn(void) 51 { 52 fprintf(stderr, 53 "nmi_watchdog enabled with topdown. May give wrong results.\n" 54 "Disable with echo 0 > /proc/sys/kernel/nmi_watchdog\n"); 55 } 56 57 #define TOPDOWN_SLOTS 0x0400 58 59 /* 60 * Check whether a topdown group supports sample-read. 61 * 62 * Only Topdown metric supports sample-read. The slots 63 * event must be the leader of the topdown group. 64 */ 65 66 bool arch_topdown_sample_read(struct evsel *leader) 67 { 68 if (!evsel__sys_has_perf_metrics(leader)) 69 return false; 70 71 if (leader->core.attr.config == TOPDOWN_SLOTS) 72 return true; 73 74 return false; 75 } 76