1 files changed, 13 insertions, 11 deletions

diff --git a/ui/src/tracks/process_scheduling/frontend.ts b/ui/src/tracks/process_scheduling/frontend.ts
index 78a0e86e7..f13e8a31d 100644
--- a/ui/src/tracks/process_scheduling/frontend.ts
+++ b/ui/src/tracks/process_scheduling/frontend.ts
@@ -31,8 +31,6 @@ import {
 
 const MARGIN_TOP = 5;
 const RECT_HEIGHT = 30;
-const TRACK_HEIGHT = MARGIN_TOP * 2 + RECT_HEIGHT;
-const SUMMARY_HEIGHT = TRACK_HEIGHT - MARGIN_TOP;
 
 class ProcessSchedulingTrack extends Track<Config, Data> {
   static readonly kind = PROCESS_SCHEDULING_TRACK_KIND;
@@ -47,22 +45,26 @@ class ProcessSchedulingTrack extends Track<Config, Data> {
     super(trackState);
   }
 
-  getHeight(): number {
-    return TRACK_HEIGHT;
-  }
-
   renderCanvas(ctx: CanvasRenderingContext2D): void {
     // TODO: fonts and colors should come from the CSS and not hardcoded here.
     const {timeScale, visibleWindowTime} = globals.frontendLocalState;
     const data = this.data();
 
+    // If there aren't enough cached slices data in |data| request more to
+    // the controller.
+    const inRange = data !== undefined &&
+        (visibleWindowTime.start >= data.start &&
+         visibleWindowTime.end <= data.end);
+    if (!inRange || data === undefined ||
+        data.resolution !== globals.getCurResolution()) {
+      globals.requestTrackData(this.trackState.id);
+    }
     if (data === undefined) return;  // Can't possibly draw anything.
 
     // If the cached trace slices don't fully cover the visible time range,
     // show a gray rectangle with a "Loading..." label.
     checkerboardExcept(
         ctx,
-        this.getHeight(),
         timeScale.timeToPx(visibleWindowTime.start),
         timeScale.timeToPx(visibleWindowTime.end),
         timeScale.timeToPx(data.start),
@@ -78,7 +80,7 @@ class ProcessSchedulingTrack extends Track<Config, Data> {
   renderSummary(ctx: CanvasRenderingContext2D, data: SummaryData): void {
     const {timeScale, visibleWindowTime} = globals.frontendLocalState;
     const startPx = Math.floor(timeScale.timeToPx(visibleWindowTime.start));
-    const bottomY = TRACK_HEIGHT;
+    const bottomY = MARGIN_TOP + RECT_HEIGHT;
 
     let lastX = startPx;
     let lastY = bottomY;
@@ -94,7 +96,7 @@ class ProcessSchedulingTrack extends Track<Config, Data> {
       lastX = Math.floor(timeScale.timeToPx(startTime));
 
       ctx.lineTo(lastX, lastY);
-      lastY = MARGIN_TOP + Math.round(SUMMARY_HEIGHT * (1 - utilization));
+      lastY = MARGIN_TOP + Math.round(RECT_HEIGHT * (1 - utilization));
       ctx.lineTo(lastX, lastY);
     }
     ctx.lineTo(lastX, bottomY);
@@ -107,7 +109,7 @@ class ProcessSchedulingTrack extends Track<Config, Data> {
     assertTrue(data.starts.length === data.ends.length);
     assertTrue(data.starts.length === data.utids.length);
 
-    const cpuTrackHeight = Math.floor(RECT_HEIGHT / data.maxCpu);
+    const cpuTrackHeight = Math.floor(RECT_HEIGHT / data.numCpus);
 
     for (let i = 0; i < data.starts.length; i++) {
       const tStart = data.starts[i];
@@ -181,7 +183,7 @@ class ProcessSchedulingTrack extends Track<Config, Data> {
       return;
     }
 
-    const cpuTrackHeight = Math.floor(RECT_HEIGHT / data.maxCpu);
+    const cpuTrackHeight = Math.floor(RECT_HEIGHT / data.numCpus);
     const cpu = Math.floor((y - MARGIN_TOP) / (cpuTrackHeight + 1));
     const {timeScale} = globals.frontendLocalState;
     const t = timeScale.pxToTime(x);