diff --git a/Cargo.toml b/Cargo.toml
index 069bbd8..7acddaa 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -20,5 +20,5 @@ license = "MIT"
 
 [workspace.dependencies]
 harness = { path = "./harness", version = "0.0" }
-harness-macros = { path = "./harness/macros", version = "0.0.1" }
-harness-probe-perf = { path = "./probes/perf", version = "0.0.4" }
+harness-macros = { path = "./harness/macros", version = "0.0.2" }
+harness-probe-perf = { path = "./probes/perf", version = "0.0.5" }
diff --git a/harness/Cargo.toml b/harness/Cargo.toml
index 94a08cc..1b4e31d 100644
--- a/harness/Cargo.toml
+++ b/harness/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "harness"
-version = "0.0.5"
+version = "0.0.6"
 description = "Precise and reproducible benchmarking"
 repository = "https://github.com/wenyuzhao/harness"
 homepage = "https://github.com/wenyuzhao/harness"
diff --git a/harness/macros/Cargo.toml b/harness/macros/Cargo.toml
index b7ff5b0..3be9f75 100644
--- a/harness/macros/Cargo.toml
+++ b/harness/macros/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "harness-macros"
-version = "0.0.1"
+version = "0.0.2"
 description = "Procedural macros for the harness crate"
 repository = "https://github.com/wenyuzhao/harness"
 homepage = "https://github.com/wenyuzhao/harness"
diff --git a/harness/macros/src/lib.rs b/harness/macros/src/lib.rs
index 43a59e3..389b3d4 100644
--- a/harness/macros/src/lib.rs
+++ b/harness/macros/src/lib.rs
@@ -130,7 +130,7 @@ pub fn probe(_attr: TokenStream, item: TokenStream) -> TokenStream {
         #input
 
         #[no_mangle]
-        pub extern "C" fn harness_register_probe(probes: &mut ProbeManager) {
+        pub extern "C" fn harness_register_probe(probes: &mut ::harness::probe::ProbeManager) {
             probes.register(Box::new(#name::default()));
         }
     };
diff --git a/harness/src/bencher.rs b/harness/src/bencher.rs
index 55c2ee3..d4b6b84 100644
--- a/harness/src/bencher.rs
+++ b/harness/src/bencher.rs
@@ -79,7 +79,7 @@ impl<'a> Drop for BenchTimer<'a> {
             *state = BencherState::AfterTiming;
         }
         let elapsed = self.start_time.elapsed();
-        self.bencher.timing_end();
+        self.bencher.timing_end(elapsed.clone());
         let mut lock = self.bencher.elapsed.lock().unwrap();
         assert!(lock.is_none(), "More than one benchmark timer detected");
         *lock = Some(elapsed);
@@ -142,12 +142,13 @@ impl Bencher {
         )
     }
 
-    fn timing_end(&self) {
+    fn timing_end(&self, walltime: Duration) {
         let mut probes = self.probes.borrow_mut();
         probes.end(
             &self.bench,
             self.current_iteration,
             !self.is_timing_iteration(),
+            walltime,
         )
     }
 
@@ -235,6 +236,17 @@ impl Bencher {
             .unwrap()
             .push((name.as_ref().to_owned(), Box::new(value)));
     }
+
+    /// Returns the wall-clock time of the last timing phase.
+    /// Returns `None` if the timing phase has not finished yet.
+    pub fn get_walltime(&self) -> Option<Duration> {
+        self.elapsed.lock().unwrap().clone()
+    }
+
+    /// Returns the value of a counter as a floating point number.
+    pub fn get_raw_counter_value(&self, name: impl AsRef<str>) -> Option<f32> {
+        self.probes.borrow().get_value(name.as_ref())
+    }
 }
 
 pub struct SingleBenchmarkRunner {
diff --git a/harness/src/probe.rs b/harness/src/probe.rs
index 5c3e194..7c52a2c 100644
--- a/harness/src/probe.rs
+++ b/harness/src/probe.rs
@@ -7,12 +7,17 @@ use serde::{de::DeserializeOwned, Deserialize, Serialize};
 
 use crate::bencher::{StatPrintFormat, Value};
 
-#[derive(Default)]
 struct Counters {
     counters: Vec<(String, f32)>,
 }
 
 impl Counters {
+    pub(crate) fn new(walltime: Duration) -> Self {
+        Self {
+            counters: vec![("time".to_owned(), walltime.as_micros() as f32 / 1000.0)],
+        }
+    }
+
     fn merge(&mut self, values: HashMap<String, f32>) {
         let mut values = values.iter().collect::<Vec<_>>();
         values.sort_by_key(|x| x.0.as_str());
@@ -20,6 +25,13 @@ impl Counters {
             self.counters.push((k.clone(), *v));
         }
     }
+
+    fn get_value(&self, name: &str) -> Option<f32> {
+        self.counters
+            .iter()
+            .find(|(k, _)| k == name)
+            .map(|(_, v)| *v)
+    }
 }
 
 #[derive(Default, Clone, Debug, Serialize, Deserialize)]
@@ -76,7 +88,6 @@ impl Probe for BaseProbe {
 }
 
 pub struct ProbeManager {
-    base_probe: BaseProbe,
     probes: Vec<Box<dyn Probe>>,
     counters: Counters,
     libraries: Vec<Library>,
@@ -85,9 +96,8 @@ pub struct ProbeManager {
 impl ProbeManager {
     pub(crate) fn new() -> Self {
         Self {
-            base_probe: BaseProbe::default(),
             probes: vec![],
-            counters: Counters::default(),
+            counters: Counters::new(Duration::ZERO),
             libraries: vec![],
         }
     }
@@ -122,7 +132,6 @@ impl ProbeManager {
             }
             probe_args.push(Some(args));
         }
-        self.base_probe.init(ProbeArgs::default());
         for (i, probe) in self.probes.iter_mut().enumerate() {
             let args = probe_args[i].take().unwrap();
             probe.init(args);
@@ -130,34 +139,40 @@ impl ProbeManager {
     }
 
     pub(crate) fn deinit(&mut self) {
-        self.base_probe.deinit();
         for probe in self.probes.iter_mut() {
             probe.deinit();
         }
     }
 
     pub(crate) fn begin(&mut self, benchmark: &str, iteration: usize, warmup: bool) {
-        self.base_probe.begin(benchmark, iteration, warmup);
         for probe in self.probes.iter_mut() {
             probe.begin(benchmark, iteration, warmup)
         }
     }
 
-    pub(crate) fn end(&mut self, benchmark: &str, iteration: usize, warmup: bool) {
+    pub(crate) fn end(
+        &mut self,
+        benchmark: &str,
+        iteration: usize,
+        warmup: bool,
+        walltime: Duration,
+    ) {
         // harness_end
-        self.base_probe.end(benchmark, iteration, warmup);
         for probe in self.probes.iter_mut() {
             probe.end(benchmark, iteration, warmup)
         }
         // report values
-        let mut counters = Counters::default();
-        counters.merge(self.base_probe.report());
+        let mut counters = Counters::new(walltime);
         for probe in self.probes.iter_mut() {
             counters.merge(probe.report());
         }
         self.counters = counters;
     }
 
+    pub(crate) fn get_value(&self, name: &str) -> Option<f32> {
+        self.counters.get_value(name)
+    }
+
     fn dump_counters_stderr_table(&self, stats: &[(String, Box<dyn Value>)]) {
         for (name, _) in stats {
             eprint!("{}\t", name);
diff --git a/probes/perf/Cargo.toml b/probes/perf/Cargo.toml
index e56e095..621b8ce 100644
--- a/probes/perf/Cargo.toml
+++ b/probes/perf/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "harness-probe-perf"
-version = "0.0.4"
+version = "0.0.5"
 description = "harness probe for reporting linux perf-event counter values"
 repository = "https://github.com/wenyuzhao/harness"
 homepage = "https://github.com/wenyuzhao/harness"
diff --git a/probes/perf/src/lib.rs b/probes/perf/src/lib.rs
index d99c770..8784489 100644
--- a/probes/perf/src/lib.rs
+++ b/probes/perf/src/lib.rs
@@ -1,9 +1,9 @@
 #[cfg(target_os = "linux")]
 use std::collections::HashMap;
 
+use harness::probe::Probe;
 #[cfg(target_os = "linux")]
 use harness::probe::ProbeArgs;
-use harness::probe::{Probe, ProbeManager};
 
 #[harness::probe]
 #[derive(Default)]