diff options
| -rw-r--r-- | llvm/tools/llvm-exegesis/lib/PerfHelper.cpp | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp b/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp index f164e3d2854..c145ea8404b 100644 --- a/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp +++ b/llvm/tools/llvm-exegesis/lib/PerfHelper.cpp @@ -96,9 +96,12 @@ Counter::Counter(const PerfEvent &Event) { const uint32_t Flags = 0; perf_event_attr AttrCopy = *Event.attribute(); FileDescriptor = perf_event_open(&AttrCopy, Pid, Cpu, GroupFd, Flags); - assert(FileDescriptor != -1 && - "Unable to open event, make sure your kernel allows user space perf " - "monitoring."); + if (FileDescriptor == -1) { + llvm::errs() << "Unable to open event, make sure your kernel allows user " + "space perf monitoring.\nYou may want to try:\n$ sudo sh " + "-c 'echo -1 > /proc/sys/kernel/perf_event_paranoid'\n"; + } + assert(FileDescriptor != -1 && "Unable to open event"); } Counter::~Counter() { close(FileDescriptor); } |
