YJIT: track time since initialization (ruby#12263)

Author: Maxime Chevalier-Boisvert

yjit.rb

@@ -389,7 +389,9 @@ def _print_stats(out: $stderr) # :nodoc:
       end
       out.puts "max_inline_versions:   " + format_number(13, stats[:max_inline_versions])
       out.puts "compiled_branch_count: " + format_number(13, stats[:compiled_branch_count])
-      out.puts "compile_time_ms:       " + format_number(13, stats[:compile_time_ns] / (1000 * 1000))
+
+      out.puts "yjit_active_ms:        " + format_number(13, stats[:yjit_active_ns] / 10**6)
+      out.puts "compile_time_ms:       " + format_number_pct(13, stats[:compile_time_ns] / 10**6 , stats[:yjit_active_ns] / 10**6)
       out.puts "block_next_count:      " + format_number(13, stats[:block_next_count])
       out.puts "defer_count:           " + format_number(13, stats[:defer_count])
       out.puts "defer_empty_count:     " + format_number(13, stats[:defer_empty_count])

yjit/src/stats.rs

@@ -12,7 +12,7 @@ use std::collections::HashMap;
 use crate::codegen::CodegenGlobals;
 use crate::cruby::*;
 use crate::options::*;
-use crate::yjit::yjit_enabled_p;
+use crate::yjit::{yjit_enabled_p, YJIT_INIT_TIME};
 
 /// Running total of how many ISeqs are in the system.
 #[no_mangle]
@@ -797,6 +797,10 @@ fn rb_yjit_gen_stats_dict(key: VALUE) -> VALUE {
         set_stat_usize!(hash, "iseq_alloc_count", rb_yjit_iseq_alloc_count as usize);
 
         set_stat!(hash, "object_shape_count", rb_object_shape_count());
+
+        // Time since YJIT init in nanoseconds
+        let time_nanos = Instant::now().duration_since(YJIT_INIT_TIME.unwrap()).as_nanos();
+        set_stat_usize!(hash, "yjit_active_ns", time_nanos as usize);
     }
 
     // If we're not generating stats, put only default counters

yjit/src/yjit.rs

@@ -8,6 +8,7 @@ use crate::stats::incr_counter;
 use crate::stats::with_compile_time;
 
 use std::os::raw::{c_char, c_int};
+use std::time::Instant;
 use crate::log::Log;
 
 /// Is YJIT on? The interpreter uses this variable to decide whether to trigger
@@ -16,6 +17,9 @@ use crate::log::Log;
 #[no_mangle]
 pub static mut rb_yjit_enabled_p: bool = false;
 
+// Time when YJIT was yjit was initialized (see yjit_init)
+pub static mut YJIT_INIT_TIME: Option<Instant> = None;
+
 /// Parse one command-line option.
 /// This is called from ruby.c
 #[no_mangle]
@@ -76,6 +80,11 @@ fn yjit_init() {
         let _ = std::fs::remove_file(&perf_map);
         println!("YJIT perf map: {perf_map}");
     }
+
+    // Note the time when YJIT was initialized
+    unsafe {
+        YJIT_INIT_TIME = Some(Instant::now());
+    }
 }
 
 #[no_mangle]