Update the table of RAM vs number of renderers

- revised my guesstimate of 25 MB per renderer to 40MB, which I think is more appropiate for long lived tabs, since short lived tabs don't really matter here.
- the lower end (< 1GB) has less total renderers
- the middle has about the same
- the upper end (> 2GB) has more renderers
- added test to open 34 tabs.

Review URL: http://codereview.chromium.org/21484

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@10024 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 52 insertions, 7 deletions

diff --git a/chrome/browser/browser_uitest.cc b/chrome/browser/browser_uitest.cc
index 5096923..efaaa45 100644
--- a/chrome/browser/browser_uitest.cc
+++ b/chrome/browser/browser_uitest.cc
@@ -4,6 +4,7 @@
 
 #include "base/file_util.h"
 #include "base/string_util.h"
+#include "base/sys_info.h"
 #include "base/values.h"
 #include "chrome/app/chrome_dll_resource.h"
 #include "chrome/common/chrome_constants.h"
@@ -85,6 +86,35 @@ TEST_F(BrowserTest, Title) {
   EXPECT_EQ(test_title, GetActiveTabTitle());
 }
 
+// Create 34 tabs and verify that a lot of processes have been created. The
+// exact number of processes depends on the amount of memory. Previously we
+// had a hard limit of 31 processes and this test is mainly directed at
+// verifying that we don't crash when we pass this limit.
+TEST_F(BrowserTest, ThirtyFourTabs) {
+  std::wstring test_file = test_data_directory_;
+  file_util::AppendToPath(&test_file, L"title2.html");
+  GURL url(net::FilePathToFileURL(test_file));
+  scoped_ptr<BrowserProxy> window(automation()->GetBrowserWindow(0));
+  // There is one initial tab.
+  for (int ix = 0; ix != 33; ++ix) {
+    EXPECT_TRUE(window->AppendTab(url));
+  }
+  int tab_count = 0;
+  EXPECT_TRUE(window->GetTabCount(&tab_count));
+  EXPECT_EQ(34, tab_count);
+  // Do not test the rest in single process mode.
+  if (in_process_renderer())
+    return;
+  // See browser\renderer_host\render_process_host.cc for the algorithm to
+  // decide how many processes to create.
+  int process_count = GetBrowserProcessCount();
+  if (base::SysInfo::AmountOfPhysicalMemoryMB() >= 2048) {
+    EXPECT_GE(process_count, 24);
+  } else {
+    EXPECT_LE(process_count, 22);
+  }
+}
+
 // The browser should quit quickly if it receives a WM_ENDSESSION message.
 TEST_F(BrowserTest, WindowsSessionEnd) {
   std::wstring test_file = test_data_directory_;
diff --git a/chrome/browser/renderer_host/render_process_host.cc b/chrome/browser/renderer_host/render_process_host.cc
index 7a9ede0..ad44ac8 100644
--- a/chrome/browser/renderer_host/render_process_host.cc
+++ b/chrome/browser/renderer_host/render_process_host.cc
@@ -16,12 +16,27 @@ unsigned int GetMaxRendererProcessCount() {
   // amount of installed memory as reported by the OS. The table
   // values are calculated by assuming that you want the renderers to
   // use half of the installed ram and assuming that each tab uses
-  // ~25MB.
+  // ~40MB, however the curve is not linear but piecewise linear with
+  // interleaved slopes of 3 and 2.
+  // If you modify this table you need to adjust browser\browser_uitest.cc
+  // to match the expected number of processes.
+
   static const int kMaxRenderersByRamTier[] = {
-    4,                                  // less than 256MB
-    8,                                  // 256MB
-    12,                                 // 512MB
-    16,                                 // 768MB
+    3,                        // less than 256MB
+    6,                        //  256MB
+    9,                        //  512MB
+    12,                       //  768MB
+    14,                       // 1024MB
+    18,                       // 1280MB
+    20,                       // 1536MB
+    22,                       // 1792MB
+    24,                       // 2048MB
+    26,                       // 2304MB
+    29,                       // 2560MB
+    32,                       // 2816MB
+    35,                       // 3072MB
+    38,                       // 3328MB
+    40                        // 3584MB
   };
 
   static unsigned int max_count = 0;
diff --git a/chrome/common/chrome_constants.cc b/chrome/common/chrome_constants.cc
index 494d3b0..9432915 100644
--- a/chrome/common/chrome_constants.cc
+++ b/chrome/common/chrome_constants.cc
@@ -46,8 +46,8 @@ const FilePath::CharType kHistoryBookmarksFileName[] =
     FPL("Bookmarks From History");
 const wchar_t kCustomDictionaryFileName[] = L"Custom Dictionary.txt";
 
-// Note, this shouldn't go above 64.  See bug 535234.
-const unsigned int kMaxRendererProcessCount = 20;
+// This number used to be limited to 32 in the past (see b/535234).
+const unsigned int kMaxRendererProcessCount = 42;
 const int kStatsMaxThreads = 32;
 const int kStatsMaxCounters = 300;