Changing OOM range to 0, 1000 and tweaking OOM algorithm.

base/process_util_linux.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/process_util.h"
 
 #include <ctype.h>
 #include <dirent.h>
 #include <dlfcn.h>
 #include <errno.h>
@@ skipping 712 matching lines @@
   // Android doesn't support setting a new handler.
   DLOG(WARNING) << "Not feasible.";
 #else
   // Set the new-out of memory handler.
   std::set_new_handler(&OnNoMemory);
   // If we're using glibc's allocator, the above functions will override
   // malloc and friends and make them die on out of memory.
 #endif
 }
 
+// NOTE: This is not the only version of this function in the source:
+// the setuid sandbox (in process_util_linux.c, in the sandbox source)
+// also has it's own C version.
 bool AdjustOOMScore(ProcessId process, int score) {
-  if (score < 0 || score > 15)
+  if (score < 0 || score > 1000)

[stevenjb, 2011/08/18 00:20:07]

bit: kMaxOOMScore instead of 1000

[Greg Spencer (Chromium), 2011/08/18 23:10:50]

Done.

     return false;
 
-  FilePath oom_adj("/proc");
-  oom_adj = oom_adj.Append(base::Int64ToString(process));
-  oom_adj = oom_adj.AppendASCII("oom_adj");
+  FilePath oom_path("/proc");
+  oom_path = oom_path.Append(base::Int64ToString(process));
 
-  if (!file_util::PathExists(oom_adj))
-    return false;
+  // Attempt to write the newer oom_score_adj file first.
+  FilePath oom_file = oom_path.AppendASCII("oom_score_adj");
+  if (file_util::PathExists(oom_file)) {
+    std::string score_str = base::IntToString(score);
+    VLOG(1) << "Adjusting oom_score_adj of " << process << " to " << score_str;
+    return (static_cast<int>(score_str.length()) ==

[stevenjb, 2011/08/18 00:20:07]

nit: size_t bytes = score_str.length() would make this easier to read (|bytes|
can also be used in WriteFile call).

[Greg Spencer (Chromium), 2011/08/18 23:10:50]

Can't be a size_t, it has to be an int, but I did split it out.

+            file_util::WriteFile(oom_file, score_str.c_str(),
+                                 score_str.length()));
+  }
 
-  std::string score_str = base::IntToString(score);
-  return (static_cast<int>(score_str.length()) ==
-          file_util::WriteFile(oom_adj, score_str.c_str(), score_str.length()));
+  // If the oom_score_adj file doesn't exist, then we write the old
+  // style file and translate the oom_adj score to the range 0-15.
+  oom_file = oom_path.AppendASCII("oom_adj");
+  if (file_util::PathExists(oom_file)) {
+    std::string score_str = base::IntToString(score * 15 / 1000);

[stevenjb, 2011/08/18 00:20:07]

nit: const for old score range also

[Greg Spencer (Chromium), 2011/08/18 23:10:50]

Done.

+    VLOG(1) << "Adjusting oom_adj of " << process << " to " << score_str;
+    return (static_cast<int>(score_str.length()) ==
+            file_util::WriteFile(oom_file, score_str.c_str(),
+                                 score_str.length()));
+  }
+
+  return false;
 }
 
 }  // namespace base