chromeos: Add swap tunable features for ChromeOS.

Adding features for ram_vs_swap_weight and extra_free kernel
tunables.

BUG=chromium:1019806
TESTED=Validated on an octopus device

Change-Id: I681e09ba7cae3deeab69a8833fa068ed09f9eaf7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1890792Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Commit-Queue: Brian Geffon <bgeffon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#710961}

chromeos/memory/swap_configuration.cc

@@ -17,14 +17,32 @@ const base::Feature kCrOSTuneMinFilelist{"CrOSTuneMinFilelist",
 
 const base::FeatureParam<int> kCrOSMinFilelistMb{&kCrOSTuneMinFilelist,
                                                  "CrOSMinFilelistMb", -1};
+
+const base::Feature kCrOSTuneRamVsSwapWeight{"CrOSTuneRamVsSwapWeight",
+                                             base::FEATURE_DISABLED_BY_DEFAULT};
+
+const base::FeatureParam<int> kCrOSRamVsSwapWeight{&kCrOSTuneRamVsSwapWeight,
+                                                   "CrOSRamVsSwapWeight", -1};
+
+const base::Feature kCrOSTuneExtraFree{"CrOSTuneExtraFree",
+                                       base::FEATURE_DISABLED_BY_DEFAULT};
+
+const base::FeatureParam<int> kCrOSExtraFreeMb{&kCrOSTuneExtraFree,
+                                               "CrOSExtraFreeMb", -1};
+
 namespace {
 
 constexpr const char kMinFilelist[] = "min_filelist";
+constexpr const char kRamVsSwapWeight[] = "ram_vs_swap_weight";
+constexpr const char kExtraFree[] = "extra_free";
 
 void OnSwapParameterSet(std::string parameter,
                         base::Optional<std::string> res) {
   LOG_IF(ERROR, !res.has_value())
       << "Setting swap paramter " << parameter << " failed.";
+  LOG_IF(ERROR, res.has_value() && !res.value().empty())
+      << "Setting swap parameter " << parameter
+      << " returned error: " << res.value();
 }
 
 void ConfigureMinFilelistIfEnabled() {
@@ -48,9 +66,54 @@ void ConfigureMinFilelistIfEnabled() {
       kMinFilelist, min_mb, base::BindOnce(&OnSwapParameterSet, kMinFilelist));
 }
 
+void ConfigureRamVsSwapWeightIfEnabled() {
+  if (!base::FeatureList::IsEnabled(kCrOSTuneRamVsSwapWeight))
+    return;
+
+  chromeos::DebugDaemonClient* debugd_client =
+      chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
+  CHECK(debugd_client);
+
+  int swap_weight = kCrOSRamVsSwapWeight.Get();
+  if (swap_weight < 0) {
+    LOG(ERROR) << "Ram vs Swap weight must be greater than or equal to 0, "
+                  "invalid value: "
+               << swap_weight;
+    return;
+  }
+
+  VLOG(1) << "Setting ram vs swap weight to: " << swap_weight;
+  debugd_client->SetSwapParameter(
+      kRamVsSwapWeight, swap_weight,
+      base::BindOnce(&OnSwapParameterSet, kRamVsSwapWeight));
+}
+
+void ConfigureExtraFreeIfEnabled() {
+  if (!base::FeatureList::IsEnabled(kCrOSTuneExtraFree))
+    return;
+
+  chromeos::DebugDaemonClient* debugd_client =
+      chromeos::DBusThreadManager::Get()->GetDebugDaemonClient();
+  CHECK(debugd_client);
+
+  int extra_free = kCrOSExtraFreeMb.Get();
+  if (extra_free < 0) {
+    LOG(ERROR)
+        << "Extra free must be greater than or equal to 0, invalid value: "
+        << extra_free;
+    return;
+  }
+
+  VLOG(1) << "Setting extra_free mb to: " << extra_free;
+  debugd_client->SetSwapParameter(
+      kExtraFree, extra_free, base::BindOnce(&OnSwapParameterSet, kExtraFree));
+}
+
 }  // namespace
 
 void ConfigureSwap() {
+  ConfigureExtraFreeIfEnabled();
+  ConfigureRamVsSwapWeightIfEnabled();
   ConfigureMinFilelistIfEnabled();
 }
 

chromeos/memory/swap_configuration.h

@@ -16,6 +16,19 @@ namespace chromeos {
 extern const base::Feature kCrOSTuneMinFilelist;
 extern const base::FeatureParam<int> kCrOSTuneMinFilelistMb;
 
+// Controls the ChromeOS /sys/kernel/mm/chromeos-low_mem/ram_vs_swap_weight
+// tunable. The number is a zero or positive number which represents how well
+// zram based swap is compressed in physical ram.
+extern const base::Feature kCrOSTuneRamVsSwapWeight;
+extern const base::FeatureParam<int> kCrOSRamVsSwapWeight;
+
+// Controls the ChromeOS /proc/sys/vm/extra_free_kbytes tunable. The number is a
+// zero or positive number which represents how much additional memory the
+// kernel will keep around. Raising this number has the affect of causing
+// swapping earlier.
+extern const base::Feature kCrOSTuneExtraFree;
+extern const base::FeatureParam<int> kCrOSExtraFreeMb;
+
 // Configure swap will configure any swap related experiments that this user may
 // be opted into.
 CHROMEOS_EXPORT void ConfigureSwap();