fix: hardware info sampler (iopsystems#53)

Fix the hardware info sampler to work on platforms such as the
raspi 4B which do not expose die and node as part of the topology.

Also fixes the cpu usage sampler for those platforms.

src/samplers/hwinfo/cache.rs

@@ -75,13 +75,13 @@ pub fn get_caches() -> Result<Vec<Vec<Cache>>> {
 
     for (index, caches) in ret.iter_mut().enumerate() {
         for cpu_id in &cpu_ids {
-            let cache = Cache::new(*cpu_id, index)?;
+            if let Ok(cache) = Cache::new(*cpu_id, index) {
+                if cache.shared_cpus[0] != *cpu_id {
+                    continue;
+                }
 
-            if cache.shared_cpus[0] != *cpu_id {
-                continue;
+                caches.push(cache);
             }
-
-            caches.push(cache);
         }
     }
 

src/samplers/hwinfo/cpu.rs

@@ -48,21 +48,28 @@ pub fn get_cpus() -> Result<Vec<Cpu>> {
     let ids = read_list("/sys/devices/system/cpu/online")?;
     for id in ids {
         let core_id = read_usize(format!("/sys/devices/system/cpu/cpu{id}/topology/core_id"))?;
-        let die_id = read_usize(format!("/sys/devices/system/cpu/cpu{id}/topology/die_id"))?;
         let package_id = read_usize(format!(
             "/sys/devices/system/cpu/cpu{id}/topology/physical_package_id"
         ))?;
 
+        // if the platform does not expose die topology, use the package id
+        let die_id = read_usize(format!("/sys/devices/system/cpu/cpu{id}/topology/die_id"))
+            .unwrap_or(package_id);
+
         let core_cpus = read_list(format!(
             "/sys/devices/system/cpu/cpu{id}/topology/core_cpus_list"
         ))?;
-        let die_cpus = read_list(format!(
-            "/sys/devices/system/cpu/cpu{id}/topology/die_cpus_list"
-        ))?;
         let package_cpus = read_list(format!(
             "/sys/devices/system/cpu/cpu{id}/topology/package_cpus_list"
         ))?;
 
+        // if the platform does not expose die topology, treat all cpus in same
+        // package as on the same die
+        let die_cpus = read_list(format!(
+            "/sys/devices/system/cpu/cpu{id}/topology/die_cpus_list"
+        ))
+        .unwrap_or(package_cpus.clone());
+
         let core_siblings = read_list(format!(
             "/sys/devices/system/cpu/cpu{id}/topology/core_siblings_list"
         ))?;

src/samplers/hwinfo/memory.rs

@@ -5,12 +5,6 @@ pub struct Memory {
     total_bytes: u64,
 }
 
-// impl Memory {
-// 	pub fn total_bytes(&self) -> u64 {
-// 		self.total_bytes
-// 	}
-// }
-
 impl Memory {
     pub fn new() -> Result<Self> {
         let file = File::open("/proc/meminfo")?;

src/samplers/hwinfo/node.rs

@@ -10,12 +10,22 @@ pub struct Node {
 pub fn get_nodes() -> Result<Vec<Node>> {
     let mut ret = Vec::new();
 
-    let ids = read_list("/sys/devices/system/node/online")?;
-
-    for id in ids {
-        let memory = Memory::node(id)?;
-        let cpus = read_list(format!("/sys/devices/system/node/node{id}/cpulist"))?;
-        ret.push(Node { id, cpus, memory });
+    if let Ok(ids) = read_list("/sys/devices/system/node/online") {
+        for id in ids {
+            let memory = Memory::node(id)?;
+            let cpus = read_list(format!("/sys/devices/system/node/node{id}/cpulist"))?;
+            ret.push(Node { id, cpus, memory });
+        }
+    } else {
+        // Some platforms might not expose node topology. For those platforms we
+        // will consider all resources part of the same node.
+        let memory = Memory::new()?;
+        let cpus = read_list("/sys/devices/system/cpu/cpu0/topology/package_cpus_list")?;
+        ret.push(Node {
+            id: 0,
+            cpus,
+            memory,
+        });
     }
 
     Ok(ret)