From f9b0bf0b5fed09ead72259f60f7edf2f37a9720d Mon Sep 17 00:00:00 2001
From: David Venhoff <david.venhoff@cs.tu-dortmund.de>
Date: Fri, 12 Sep 2025 11:53:11 +0200
Subject: [PATCH] Correct for errors in the current tsc by using cyc

---
 pt-dump-decoder/src/lib.rs | 27 +++++++++++++++++----------
 1 file changed, 17 insertions(+), 10 deletions(-)

diff --git a/pt-dump-decoder/src/lib.rs b/pt-dump-decoder/src/lib.rs
index 3f719f7..5f8e0bf 100644
--- a/pt-dump-decoder/src/lib.rs
+++ b/pt-dump-decoder/src/lib.rs
@@ -49,10 +49,17 @@ pub fn analyze_dump(
     let f_bus = cpuid!(0x16).ecx as f64 * 1_000_000.0;
     let mut current_cbr = 0u8;
 
+    // Keeps track of the cycles since the last tsc for higher accuracy
+    let mut duration_since_last_tsc = Duration::ZERO;
     // Records the first tsc after the ptwrite (42) message
-    let mut first_tsc_main = None::<u64>;
+    let mut first_tsc_main = None::<f64>;
     // Records the first tsc after the ptwrite (43) message
-    let mut first_tsc_post_run = None::<u64>;
+    let mut first_tsc_post_run = None::<f64>;
+    let f_tsc = CpuId::new()
+        .get_tsc_info()
+        .unwrap()
+        .tsc_frequency()
+        .unwrap();
 
     let mut seen_cbrs = HashMap::<u8, u64>::new();
 
@@ -67,17 +74,22 @@ pub fn analyze_dump(
                 }
                 let f_core = f_bus * current_cbr as f64;
                 let duration = Duration::from_secs_f64(cyc.value() as f64 / f_core);
+                duration_since_last_tsc += duration;
                 segments.last_mut().unwrap().1 += duration;
             }
             Ok(Packet::Tsc(tsc)) => {
+                let tsc_seconds = tsc.tsc() as f64 / f_tsc as f64;
+                let corrected_tsc = tsc_seconds + duration_since_last_tsc.as_secs_f64();
+                duration_since_last_tsc = Duration::ZERO;
+
                 if let [.., (Scope::Main, _)] = segments.as_slice()
                     && first_tsc_main.is_none()
                 {
-                    first_tsc_main = Some(tsc.tsc());
+                    first_tsc_main = Some(corrected_tsc);
                 } else if let [.., (Scope::PostRun, _)] = segments.as_slice()
                     && first_tsc_post_run.is_none()
                 {
-                    first_tsc_post_run = Some(tsc.tsc());
+                    first_tsc_post_run = Some(corrected_tsc);
                 }
             }
             Ok(Packet::Cbr(cbr)) => {
@@ -106,12 +118,7 @@ pub fn analyze_dump(
     let duration_total = segments.iter().map(|(_, duration)| *duration).sum();
     let main_duration = duration_in_mode(&segments, Scope::Main);
 
-    let f_tsc = CpuId::new()
-        .get_tsc_info()
-        .unwrap()
-        .tsc_frequency()
-        .unwrap();
-    let total_seconds_tsc = (first_tsc_post_run.unwrap() - first_tsc_main.unwrap()) as f64 / f_tsc as f64;
+    let total_seconds_tsc = first_tsc_post_run.unwrap() - first_tsc_main.unwrap();
 
     Ok(AnalyzeData {
         packets: total,