libkperf/0005-pmu-event.patch

From 4a084d12ceb0129c8b901798282ef89f3df13bf2 Mon Sep 17 00:00:00 2001
From: ganlixiong <ganli2012@gmail.com>
Date: Fri, 11 Oct 2024 10:50:07 +0800
Subject: [PATCH 05/20] =?UTF-8?q?=E4=BF=AE=E5=A4=8D=E5=9C=A8=E6=9F=90?=
 =?UTF-8?q?=E4=BA=9B=E7=8E=AF=E5=A2=83=E4=B8=8A=E6=97=A0=E6=B3=95=E8=AF=BB?=
 =?UTF-8?q?=E5=8F=96=E5=88=B0pmu=20event=E7=9A=84=E9=97=AE=E9=A2=98?=
 =?UTF-8?q?=E3=80=82?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

问题：
在某些环境上调用PmuEventList，返回的事件列表为空。

原因：
该环境上的arm core设备名称为armv8_pmuv3，而在查询事件列表时，搜索了armv8_pmuv3_0设备的事件。

解决方法：
动态寻找arm core设备，而不是用硬编码。参考perf
tool的实现，查询devices下面的所有设备，如果设备下面包含文件cpus，那么认为该设备为arm
core设备。
---
 pmu/pfm/core.cpp       | 44 +++++++++++++++++++++++++++++++++++++++---
 pmu/pfm/core.h         |  2 ++
 pmu/pmu_event_list.cpp | 10 ++++++++--
 3 files changed, 51 insertions(+), 5 deletions(-)

diff --git a/pmu/pfm/core.cpp b/pmu/pfm/core.cpp
index 80d5e0b..0ab4607 100644
--- a/pmu/pfm/core.cpp
+++ b/pmu/pfm/core.cpp
@@ -15,6 +15,7 @@
 #include <vector>
 #include <unordered_map>
 #include <fstream>
+#include <dirent.h>
 #include "pmu_event.h"
 #include "core.h"
 #include "common.h"
@@ -22,7 +23,7 @@
 using namespace std;
 using PMU_PAIR = std::pair<std::string, KUNPENG_PMU::CoreConfig>;
 static CHIP_TYPE g_chipType = UNDEFINED_TYPE;
-
+static string pmuDevice = "";
 
 namespace SOFTWARE_EVENT {
     PMU_PAIR ALIGNMENT_FAULTS = {
@@ -853,7 +854,11 @@ static struct PmuEvt* ConstructPmuEvtFromCore(KUNPENG_PMU::CoreConfig config, in
 
 static int64_t GetKernelCoreEventConfig(const string &name)
 {
-    string eventPath = "/sys/devices/armv8_pmuv3_0/events/" + name;
+    auto pmuDevicePath = GetPmuDevicePath();
+    if (pmuDevicePath.empty()) {
+        return -1;
+    }
+    string eventPath = pmuDevicePath + "/events/" + name;
     string realPath = GetRealPath(eventPath);
     if (!IsValidPath(realPath)) {
         return -1;
@@ -874,7 +879,11 @@ static int64_t GetKernelCoreEventConfig(const string &name)
 
 static int64_t GetKernelCoreEventType()
 {
-    string eventPath = "/sys/devices/armv8_pmuv3_0/type";
+    auto pmuDevicePath = GetPmuDevicePath();
+    if (pmuDevicePath.empty()) {
+        return -1;
+    }
+    string eventPath = pmuDevicePath + "/type";
     string realPath = GetRealPath(eventPath);
     if (!IsValidPath(realPath)) {
         return -1;
@@ -917,4 +926,33 @@ struct PmuEvt* GetCoreEvent(const char* pmuName, int collectType)
         return ConstructPmuEvtFromCore(KUNPENG_PMU::CORE_EVENT_MAP.at(g_chipType).at(pmuName), collectType);
     }
         return ConstructPmuEvtFromKernel(pmuName, collectType);
+}
+
+std::string GetPmuDevicePath()
+{
+    if (!pmuDevice.empty()) {
+        return pmuDevice;
+    }
+
+    static const string DEVICE_PATH = "/sys/bus/event_source/devices/";
+    DIR *dir = opendir(DEVICE_PATH.c_str());
+    if (dir == nullptr) {
+        return "";
+    }
+    struct dirent *dent;
+    while (dent = readdir(dir)) {
+        if (!strcmp(dent->d_name, ".") || !strcmp(dent->d_name, "..") || !strcmp(dent->d_name, "cpu")) {
+            continue;
+        }
+
+        // look for devices like /sys/bus/event_source/devices/armv8_pmuv3_0/cpus.
+        // Refer to function <is_arm_pmu_core> in kernel.
+        string armPmuPath = DEVICE_PATH + dent->d_name + "/cpus";
+        if (ExistPath(armPmuPath)) {
+            pmuDevice = DEVICE_PATH + dent->d_name;
+            break;
+        }
+    }
+
+    return pmuDevice;
 }
\ No newline at end of file
diff --git a/pmu/pfm/core.h b/pmu/pfm/core.h
index 0df6a25..4ecf3fe 100644
--- a/pmu/pfm/core.h
+++ b/pmu/pfm/core.h
@@ -24,5 +24,7 @@ namespace KUNPENG_PMU {
 
 struct PmuEvt* GetCoreEvent(const char* pmuName, int collectType);
 
+std::string GetPmuDevicePath();
+
 #endif
 
diff --git a/pmu/pmu_event_list.cpp b/pmu/pmu_event_list.cpp
index 2007561..c4cf226 100644
--- a/pmu/pmu_event_list.cpp
+++ b/pmu/pmu_event_list.cpp
@@ -127,10 +127,16 @@ const char** QueryCoreEvent(unsigned *numEvt)
     }
     DIR* dir;
     struct dirent* entry;
-    string path = "/sys/devices/armv8_pmuv3_0/events/";
+    auto pmuDevPath = GetPmuDevicePath();
+    if (pmuDevPath.empty()) {
+        *numEvt = coreEventList.size();
+        return coreEventList.data(); 
+    }
+    string path = pmuDevPath + "/events/";
     dir = opendir(path.c_str());
     if (dir == nullptr) {
-        return nullptr;
+        *numEvt = coreEventList.size();
+        return coreEventList.data();
     }
     while ((entry = readdir(dir)) != nullptr) {
         if (entry->d_type == DT_REG) {
-- 
2.43.0