Try #5911:

crates/bevy_diagnostic/src/lib.rs

@@ -2,13 +2,14 @@ mod diagnostic;
 mod entity_count_diagnostics_plugin;
 mod frame_time_diagnostics_plugin;
 mod log_diagnostics_plugin;
-use bevy_log::info;
+mod system_information_diagnostics_plugin;
+
+use bevy_app::prelude::*;
 pub use diagnostic::*;
 pub use entity_count_diagnostics_plugin::EntityCountDiagnosticsPlugin;
 pub use frame_time_diagnostics_plugin::FrameTimeDiagnosticsPlugin;
 pub use log_diagnostics_plugin::LogDiagnosticsPlugin;
-
-use bevy_app::prelude::*;
+pub use system_information_diagnostics_plugin::SystemInformationDiagnosticsPlugin;
 
 /// Adds core diagnostics resources to an App.
 #[derive(Default)]
@@ -17,61 +18,10 @@ pub struct DiagnosticsPlugin;
 impl Plugin for DiagnosticsPlugin {
     fn build(&self, app: &mut App) {
         app.init_resource::<Diagnostics>()
-            .add_startup_system(log_system_info);
+            .add_startup_system(system_information_diagnostics_plugin::internal::log_system_info);
     }
 }
 
 /// The width which diagnostic names will be printed as
 /// Plugin names should not be longer than this value
 pub const MAX_DIAGNOSTIC_NAME_WIDTH: usize = 32;
-
-#[derive(Debug)]
-// This is required because the Debug trait doesn't detect it's used when it's only used in a print :(
-#[allow(dead_code)]
-struct SystemInfo {
-    os: String,
-    kernel: String,
-    cpu: String,
-    core_count: String,
-    memory: String,
-}
-
-const BYTES_TO_GIB: f64 = 1.0 / 1024.0 / 1024.0 / 1024.0;
-
-fn log_system_info() {
-    // NOTE: sysinfo fails to compile when using bevy dynamic or on iOS and does nothing on wasm
-    #[cfg(all(
-        any(
-            target_os = "linux",
-            target_os = "windows",
-            target_os = "android",
-            target_os = "macos"
-        ),
-        not(feature = "bevy_dynamic_plugin")
-    ))]
-    {
-        use sysinfo::{CpuExt, SystemExt};
-
-        let mut sys = sysinfo::System::new();
-        sys.refresh_cpu();
-        sys.refresh_memory();
-
-        let info = SystemInfo {
-            os: sys
-                .long_os_version()
-                .unwrap_or_else(|| String::from("not available")),
-            kernel: sys
-                .kernel_version()
-                .unwrap_or_else(|| String::from("not available")),
-            cpu: sys.global_cpu_info().brand().trim().to_string(),
-            core_count: sys
-                .physical_core_count()
-                .map(|x| x.to_string())
-                .unwrap_or_else(|| String::from("not available")),
-            // Convert from Bytes to GibiBytes since it's probably what people expect most of the time
-            memory: format!("{:.1} GiB", sys.total_memory() as f64 * BYTES_TO_GIB),
-        };
-
-        info!("{:?}", info);
-    }
-}

crates/bevy_diagnostic/src/system_information_diagnostics_plugin.rs

@@ -0,0 +1,159 @@
+use crate::DiagnosticId;
+use bevy_app::{App, Plugin};
+
+/// Adds a System Information Diagnostic, specifically `cpu_usage` (in %) and `mem_usage` (in %)
+///
+/// Supported targets:
+/// * linux,
+/// * windows,
+/// * android,
+/// * macos
+///
+/// NOT supported when using the `bevy/dynamic` feature even when using previously mentioned targets
+#[derive(Default)]
+pub struct SystemInformationDiagnosticsPlugin;
+impl Plugin for SystemInformationDiagnosticsPlugin {
+    fn build(&self, app: &mut App) {
+        app.add_startup_system(internal::setup_system)
+            .add_system(internal::diagnostic_system);
+    }
+}
+
+impl SystemInformationDiagnosticsPlugin {
+    pub const CPU_USAGE: DiagnosticId =
+        DiagnosticId::from_u128(78494871623549551581510633532637320956);
+    pub const MEM_USAGE: DiagnosticId =
+        DiagnosticId::from_u128(42846254859293759601295317811892519825);
+}
+
+// NOTE: sysinfo fails to compile when using bevy dynamic or on iOS and does nothing on wasm
+#[cfg(all(
+    any(
+        target_os = "linux",
+        target_os = "windows",
+        target_os = "android",
+        target_os = "macos"
+    ),
+    not(feature = "bevy_dynamic_plugin")
+))]
+pub mod internal {
+    use bevy_ecs::{prelude::ResMut, system::Local};
+    use bevy_log::info;
+    use sysinfo::{CpuExt, System, SystemExt};
+
+    use crate::{Diagnostic, Diagnostics};
+
+    const BYTES_TO_GIB: f64 = 1.0 / 1024.0 / 1024.0 / 1024.0;
+
+    pub(crate) fn setup_system(mut diagnostics: ResMut<Diagnostics>) {
+        diagnostics.add(
+            Diagnostic::new(
+                super::SystemInformationDiagnosticsPlugin::CPU_USAGE,
+                "cpu_usage",
+                20,
+            )
+            .with_suffix("%"),
+        );
+        diagnostics.add(
+            Diagnostic::new(
+                super::SystemInformationDiagnosticsPlugin::MEM_USAGE,
+                "mem_usage",
+                20,
+            )
+            .with_suffix("%"),
+        );
+    }
+
+    pub(crate) fn diagnostic_system(
+        mut diagnostics: ResMut<Diagnostics>,
+        mut sysinfo: Local<Option<System>>,
+    ) {
+        if sysinfo.is_none() {
+            *sysinfo = Some(System::new_all());
+        }
+        let Some(sys) = sysinfo.as_mut() else {
+            return;
+        };
+
+        sys.refresh_cpu();
+        sys.refresh_memory();
+        let current_cpu_usage = {
+            let mut usage = 0.0;
+            let cpus = sys.cpus();
+            for cpu in cpus {
+                usage += cpu.cpu_usage(); // NOTE: this returns a value from 0.0 to 100.0
+            }
+            // average
+            usage / cpus.len() as f32
+        };
+        // `memory()` fns return a value in bytes
+        let total_mem = sys.total_memory() as f64 / BYTES_TO_GIB;
+        let used_mem = sys.used_memory() as f64 / BYTES_TO_GIB;
+        let current_used_mem = used_mem / total_mem * 100.0;
+
+        diagnostics.add_measurement(super::SystemInformationDiagnosticsPlugin::CPU_USAGE, || {
+            current_cpu_usage as f64
+        });
+        diagnostics.add_measurement(super::SystemInformationDiagnosticsPlugin::MEM_USAGE, || {
+            current_used_mem
+        });
+    }
+
+    #[derive(Debug)]
+    // This is required because the Debug trait doesn't detect it's used when it's only used in a print :(
+    #[allow(dead_code)]
+    struct SystemInfo {
+        os: String,
+        kernel: String,
+        cpu: String,
+        core_count: String,
+        memory: String,
+    }
+
+    pub(crate) fn log_system_info() {
+        let mut sys = sysinfo::System::new();
+        sys.refresh_cpu();
+        sys.refresh_memory();
+
+        let info = SystemInfo {
+            os: sys
+                .long_os_version()
+                .unwrap_or_else(|| String::from("not available")),
+            kernel: sys
+                .kernel_version()
+                .unwrap_or_else(|| String::from("not available")),
+            cpu: sys.global_cpu_info().brand().trim().to_string(),
+            core_count: sys
+                .physical_core_count()
+                .map(|x| x.to_string())
+                .unwrap_or_else(|| String::from("not available")),
+            // Convert from Bytes to GibiBytes since it's probably what people expect most of the time
+            memory: format!("{:.1} GiB", sys.total_memory() as f64 * BYTES_TO_GIB),
+        };
+
+        info!("{:?}", info);
+    }
+}
+
+#[cfg(not(all(
+    any(
+        target_os = "linux",
+        target_os = "windows",
+        target_os = "android",
+        target_os = "macos"
+    ),
+    not(feature = "bevy_dynamic_plugin")
+)))]
+pub mod internal {
+    pub(crate) fn setup_system() {
+        bevy_log::warn!("This platform and/or configuration is not supported!");
+    }
+
+    pub(crate) fn diagnostic_system() {
+        // no-op
+    }
+
+    pub(crate) fn log_system_info() {
+        // no-op
+    }
+}

examples/diagnostics/log_diagnostics.rs

@@ -17,5 +17,7 @@ fn main() {
         // .add_plugin(bevy::diagnostic::EntityCountDiagnosticsPlugin::default())
         // Uncomment this to add an asset count diagnostics:
         // .add_plugin(bevy::asset::diagnostic::AssetCountDiagnosticsPlugin::<Texture>::default())
+        // Uncomment this to add system info diagnostics:
+        // .add_plugin(bevy::diagnostic::SystemInformationDiagnosticsPlugin::default())
         .run();
 }