GPU: Adjust memory and use the soft-limit.

ui/gl/gl_context_android.cc

Index: ui/gl/gl_context_android.cc
diff --git a/ui/gl/gl_context_android.cc b/ui/gl/gl_context_android.cc
index a9e888b203d41a2912d0e87217ae1a415660013a..f4555a2c28f93fba09d8e5f8c10afff3cd992a2d 100644
--- a/ui/gl/gl_context_android.cc
+++ b/ui/gl/gl_context_android.cc
@@ -108,27 +108,33 @@ bool GLContextEGL::GetTotalGpuMemory(size_t* bytes) {
   // Now we take a default of 1/8th of memory on high-memory devices,
   // and gradually scale that back for low-memory devices (to be nicer
   // to other apps so they don't get killed). Examples:
-  // Nexus 4/10(2GB)    256MB
-  // Droid Razr M(1GB)  91MB
-  // Galaxy Nexus(1GB)  85MB
-  // Xoom(1GB)          85MB
-  // Nexus S(low-end)   8MB
+  // Nexus 4/10(2GB)    256MB (normally 128MB)
+  // Droid Razr M(1GB)  114MB (normally 57MB)
+  // Galaxy Nexus(1GB)  100MB (normally 50MB)
+  // Xoom(1GB)          100MB (normally 50MB)
+  // Nexus S(low-end)   12MB (normally 8MB)
+  // Note that the compositor now uses only some of this memory for
+  // pre-painting and uses the rest only for 'emergencies'.

[klobag.chromium, 2014/02/15 07:27:20]

Can we move this two lines up and say the number is emergency (pre-painting)? 

[epenner, 2014/02/17 05:43:23]

Yes, much better way to explain the numbers.

   static size_t limit_bytes = 0;
   if (limit_bytes == 0) {
+    // NOTE: Non-low-end devices use only 50% of these limits,
+    // except during 'emergencies' where 100% can be used.
     if (!base::android::SysUtils::IsLowEndDevice()) {
       if (physical_memory_mb >= 1536)
-        limit_bytes = physical_memory_mb / 8;
+        limit_bytes = physical_memory_mb / 8; // >192MB
       else if (physical_memory_mb >= 1152)
-        limit_bytes = physical_memory_mb / 10;
+        limit_bytes = physical_memory_mb / 8; // >144MB

[klobag.chromium, 2014/02/15 07:27:20]

merge the above two?

[epenner, 2014/02/17 05:43:23]

Good point will do. I think this number is common way to differentiate some
devices, but no longer useful here.

       else if (physical_memory_mb >= 768)
-        limit_bytes = physical_memory_mb / 12;
+        limit_bytes = physical_memory_mb / 10; // >76MB
       else
-        limit_bytes = physical_memory_mb / 16;
+        limit_bytes = physical_memory_mb / 12; // <64MB
     } else {
       // Low-end devices have 512MB or less memory by definition
       // so we hard code the limit rather than relying on the heuristics
       // above. Low-end devices use 4444 textures so we can use a lower limit.
-      limit_bytes = 8;
+      // NOTE: Low-end uses 2/3 (67%) of this memory in practice, so we have
+      // increased the limit to 12 (8MB, or 12MB in emergencies).
+      limit_bytes = 12;
     }
     limit_bytes = limit_bytes * 1024 * 1024;
   }