From a5d226503d9bf1edd6cbdf8e73b43967f70307d4 Mon Sep 17 00:00:00 2001
From: Nils Pukropp <nils@narl.io>
Date: Sun, 22 Feb 2026 23:53:10 +0100
Subject: [PATCH] feat: implement PSS (Proportional Set Size) for accurate real
 memory tracking

---
 src-tauri/src/main.rs | 29 +++++++++++++++++++++++++++--
 src/App.tsx           |  4 ++--
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src-tauri/src/main.rs b/src-tauri/src/main.rs
index 9e9d7e1..908a8f5 100644
--- a/src-tauri/src/main.rs
+++ b/src-tauri/src/main.rs
@@ -10,6 +10,29 @@ use tauri::State;
 use serde::{Serialize, Deserialize};
 use std::collections::HashMap;
 use chrono::{DateTime, Utc};
+use std::fs;
+
+// --- Helper for Real Memory (PSS) on Linux ---
+
+fn get_pss(pid: u32) -> Option<u64> {
+    // PSS (Proportional Set Size) is the most accurate "real" memory metric.
+    // It counts private memory + proportional share of shared libraries.
+    // smaps_rollup is a fast way to get this on modern Linux kernels.
+    let path = format!("/proc/{}/smaps_rollup", pid);
+    if let Ok(contents) = fs::read_to_string(path) {
+        for line in contents.lines() {
+            if line.starts_with("Pss:") {
+                let parts: Vec<&str> = line.split_whitespace().collect();
+                if parts.len() >= 2 {
+                    if let Ok(kb) = parts[1].parse::<u64>() {
+                        return Some(kb * 1024);
+                    }
+                }
+            }
+        }
+    }
+    None
+}
 
 // --- Data Structures ---
 
@@ -139,12 +162,13 @@ fn get_system_stats(
         sys.processes().iter()
             .map(|(pid, process)| {
                 let pid_u32 = pid.as_u32();
+                let memory = get_pss(pid_u32).unwrap_or_else(|| process.memory());
                 ProcessStats {
                     pid: pid_u32,
                     parent_pid: process.parent().map(|p| p.as_u32()),
                     name: process.name().to_string_lossy().to_string(),
                     cpu_usage: process.cpu_usage(),
-                    memory: process.memory(),
+                    memory,
                     status: format!("{:?}", process.status()),
                     user_id: process.user_id().map(|uid| uid.to_string()),
                     is_syspulse: is_descendant_of(pid_u32, self_pid, &sys),
@@ -159,12 +183,13 @@ fn get_system_stats(
             processes = sys.processes().iter()
                 .map(|(pid, process)| {
                     let pid_u32 = pid.as_u32();
+                    let memory = get_pss(pid_u32).unwrap_or_else(|| process.memory());
                     ProcessStats {
                         pid: pid_u32,
                         parent_pid: process.parent().map(|p| p.as_u32()),
                         name: process.name().to_string_lossy().to_string(),
                         cpu_usage: process.cpu_usage(),
-                        memory: process.memory(),
+                        memory,
                         status: format!("{:?}", process.status()),
                         user_id: process.user_id().map(|uid| uid.to_string()),
                         is_syspulse: is_descendant_of(pid_u32, self_pid, &sys),
diff --git a/src/App.tsx b/src/App.tsx
index 0293d43..fb266d0 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -580,8 +580,8 @@ function ReportView({ report, onBack }: { report: ProfilingReport, onBack: () =>
           </div>
 
           <div className="p-4 bg-surface0/50 border-t border-surface1 text-[9px] text-overlay1 font-medium italic flex items-center gap-2">
-            <AlertTriangle size={10} />
-            <span>Memory is Resident Set Size (RSS). Summed totals may exceed physical RAM due to shared segments.</span>
+            <Shield size={10} className="text-blue" />
+            <span>Memory is Proportional Set Size (PSS). It includes private memory plus a proportional share of shared libraries, providing an accurate sum of total system impact.</span>
           </div>
         </div>