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Commit `f729188530f0`

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atagen <boss@atagen.co>2026-10-17 05:56 UTC

1 file changed+34-1

monolith: log direct scanout and per-frame compositor CPU

The M7 targets need numbers, and only slow frames were logged. The frame rate line now carries the p99 compositor CPU per frame and how many frames went straight to the primary plane. Scanout switching on or off is logged with the element and plane counts, which narrows down what kept a fullscreen window from scanning out.

Modified file: crates/monolith/src/drm.rs+34 additions−1 deletions@@ -12,7 +12,7 @@ use monolith_layout::{OutputId, Rect};
 use smithay::backend::allocator::Fourcc;
 use smithay::backend::allocator::gbm::{GbmAllocator, GbmBufferFlags, GbmDevice};
 use smithay::backend::drm::VrrSupport;
-use smithay::backend::drm::compositor::FrameFlags;
+use smithay::backend::drm::compositor::{FrameFlags, PrimaryPlaneElement};
 use smithay::backend::drm::exporter::gbm::GbmFramebufferExporter;
 use smithay::backend::drm::output::{DrmOutput, DrmOutputManager, DrmOutputRenderElements};
 use smithay::backend::drm::{
@@ -86,6 +86,12 @@ struct Surface {
     vrr_on: bool,
     /// Only the cursor moved, which under VRR is drawn at a capped rate.
     cursor_redraw: bool,
+    /// The last frame went straight to the primary plane without compositing.
+    scanout: bool,
+    /// Frames scanned out and per-frame compositor CPU times since
+    /// `stats_since`, for the targets in decisions.md.
+    scanned_out: u32,
+    frame_cpu_ns: Vec<u64>,
 }
 
 impl Surface {
@@ -358,6 +364,9 @@ fn connect(state: &mut State, connector: connector::Info, crtc: crtc::Handle) {
             vrr_capable,
             vrr_on: false,
             cursor_redraw: false,
+            scanout: false,
+            scanned_out: 0,
+            frame_cpu_ns: Vec::new(),
             refresh_ns: 1_000_000_000_000 / u64::from(wl_mode.refresh.max(1) as u32),
         },
     );
@@ -431,14 +440,21 @@ fn on_vblank(state: &mut State, crtc: crtc::Handle, meta: &mut Option<DrmEventMe
             // Under VRR the panel waits for each flip, so the nominal refresh
             // says nothing about how many vblanks there were.
             let vblanks = (!surface.vrr_on).then(|| window / surface.refresh_ns.max(1));
+            let cpu = &mut surface.frame_cpu_ns;
+            cpu.sort_unstable();
+            let p99 = cpu.get(cpu.len().saturating_sub(1) * 99 / 100).copied();
             tracing::debug!(
                 output = surface.output.name(),
                 presented = surface.presented,
                 vblanks,
                 vrr = surface.vrr_on,
+                scanned_out = surface.scanned_out,
+                cpu_p99_us = p99.map(|ns| ns / 1000),
                 budget_us = surface.budget.ns() / 1000,
                 "frame rate"
             );
+            cpu.clear();
+            surface.scanned_out = 0;
             surface.presented = 0;
             surface.stats_since = t;
         }
@@ -588,6 +604,7 @@ fn render_surface(state: &mut State, crtc: crtc::Handle, target: u64) -> bool {
         }
     }
     let began = std::time::Instant::now();
+    let frame_cpu_began = thread_cpu_ns();
     let now = target;
     if wm.layout.output(surface.id).is_none() {
         return false;
@@ -612,6 +629,21 @@ fn render_surface(state: &mut State, crtc: crtc::Handle, target: u64) -> bool {
         .render_frame(renderer, &elements, CLEAR, drm.frame_flags)
     {
         Ok(result) if !result.is_empty => {
+            let direct = matches!(result.primary_element, PrimaryPlaneElement::Element(_));
+            if direct {
+                surface.scanned_out += 1;
+            }
+            if direct != surface.scanout {
+                surface.scanout = direct;
+                tracing::info!(
+                    output = surface.output.name(),
+                    scanout = direct,
+                    elements = elements.len(),
+                    overlay_planes = result.overlay_elements.len(),
+                    cursor_plane = result.cursor_element.is_some(),
+                    "direct scanout"
+                );
+            }
             let queue_began = std::time::Instant::now();
             match surface.drm.queue_frame(()) {
                 Ok(()) => {
@@ -630,6 +662,7 @@ fn render_surface(state: &mut State, crtc: crtc::Handle, target: u64) -> bool {
     let render_ns = render_began.elapsed().as_nanos() as u64 - queue_ns;
     let took = began.elapsed().as_nanos() as u64;
     surface.budget.record(took);
+    surface.frame_cpu_ns.push(thread_cpu_ns() - frame_cpu_began);
     if took > surface.refresh_ns / 2 {
         tracing::debug!(
             output = surface.output.name(),

monolith

Commit f729188530f0

Commit `f729188530f0`