Fall back to a non-hardware event source by default if `perf_event_op…

…en` fails
koute · Jul 28, 2021 · 609fbaa · 609fbaa
1 parent 2d8a5ee
commit 609fbaa
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git a/src/args.rs b/src/args.rs
@@ -174,7 +174,6 @@ pub struct RecordArgs {
     #[structopt(
         long,
         short = "s",
-        default_value = "hw_cpu_cycles",
         parse(from_str = "parse_event_source"),
         raw(possible_values = r#"&[
             "hw_cpu_cycles",
@@ -184,7 +183,7 @@ pub struct RecordArgs {
             "sw_dummy"
         ]"#)
     )]
-    pub event_source: EventSource,
+    pub event_source: Option< EventSource >,
 
     /// Size of the gathered stack payloads (in bytes)
     #[structopt(long, default_value = "24576")]

diff --git a/src/cmd_record.rs b/src/cmd_record.rs
@@ -8,7 +8,7 @@ use nwind::arch::Registers;
 use nwind::DwarfRegs;
 
 use crate::args;
-use perf_event_open::{Event, CommEvent, Mmap2Event};
+use perf_event_open::{Event, EventSource, CommEvent, Mmap2Event};
 use crate::perf_group::PerfGroup;
 use crate::perf_arch;
 use crate::archive::{ContextSwitchKind, Packet};
@@ -59,7 +59,12 @@ pub fn main( args: args::RecordArgs ) -> Result< (), Box< dyn Error > > {
     });
 
     info!( "Opening perf events for process with PID {}...", controller.pid() );
-    let mut perf = match PerfGroup::open( controller.pid(), args.frequency, args.stack_size, args.event_source ) {
+    let mut perf = PerfGroup::open( controller.pid(), args.frequency, args.stack_size, args.event_source.unwrap_or( EventSource::HwCpuCycles ) );
+    if perf.is_err() && args.event_source.is_none() {
+        perf = PerfGroup::open( controller.pid(), args.frequency, args.stack_size, args.event_source.unwrap_or( EventSource::SwCpuClock ) );
+    }
+
+    let mut perf = match perf {
         Ok( perf ) => perf,
         Err( error ) => {
             error!( "Failed to start profiling: {}", error );