base/thread: Add a new switch for chromeos scheduler tunings

For urgent threads, Chrome is now using uclamp util_min value(20)
to boost the performance instead of schedtune settings from external
upstart scripts.

This patch adds a new 'scheduler-boost-urgent=xxx' switch which makes
those urgent threads can have more aggressive boost values (0~100).

This might be needed for some ChromeOS platforms who can get better
performance from higher boosting value (e.g. Trogdor's power_VideoCall).

Additionally, existing Feature parameter names for uclamp changed to
have more general meanings:
  { MinUrgent, MaxNonUrgent, LatencySensitive } -->
  { BoostUrgent, LimitNonUrgent, LatencyTune }

BUG=1041117,b:159370915
TEST=check /proc/*/sched for all urgent threads
Signed-off-by: Ikjoon Jang <ikjn@chromium.org>
Change-Id: I07b19ed748ffba9d9a45c76310635dc359e557af
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2477712Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Reviewed-by: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Cr-Commit-Position: refs/heads/master@{#837001}

base/base_switches.cc

@@ -164,4 +164,13 @@ const char kForceFieldTrialParams[] = "force-fieldtrial-params";
 const char kEnableThreadInstructionCount[] = "enable-thread-instruction-count";
 #endif
 
+#if BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS)
+// Override the default scheduling boosting value for urgent tasks.
+// This can be adjusted if a specific chromeos device shows better perf/power
+// ratio (e.g. by running video conference tests).
+// Currently, this values directs to linux scheduler's utilization min clamp.
+// Range is 0(no biased load) ~ 100(mamximum load value).
+const char kSchedulerBoostUrgent[] = "scheduler-boost-urgent";
+#endif
+
 }  // namespace switches

base/base_switches.h

@@ -62,6 +62,10 @@ extern const char kForceFieldTrialParams[];
 extern const char kEnableThreadInstructionCount[];
 #endif
 
+#if BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS)
+extern const char kSchedulerBoostUrgent[];
+#endif
+
 }  // namespace switches
 
 #endif  // BASE_BASE_SWITCHES_H_

base/threading/platform_thread_linux.cc

@@ -10,6 +10,8 @@
 #include <cstdint>
 #include <atomic>
 
+#include "base/base_switches.h"
+#include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/feature_list.h"
 #include "base/files/file_util.h"
@@ -42,7 +44,15 @@ namespace {
 
 #if BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS)
 std::atomic<bool> g_use_sched_util(true);
-std::atomic<bool> g_feature_checked(false);
+std::atomic<bool> g_scheduler_hints_adjusted(false);
+
+const int kSchedulerBoostDef = 20;
+const int kSchedulerLimitDef = 100;
+const bool kSchedulerUseLatencyTuneDef = true;
+
+int g_scheduler_boost_adj;
+int g_scheduler_limit_adj;
+bool g_scheduler_use_latency_tune_adj;
 
 #if !defined(OS_NACL) && !defined(OS_AIX)
 // sched_attr is used to set scheduler attributes for Linux. It is not a POSIX
@@ -161,18 +171,14 @@ void SetThreadLatencySensitivity(ProcessId process_id,
     return;
 
   // FieldTrial API can be called only once features were parsed.
-  if (g_feature_checked.load()) {
-    uclamp_min_urgent =
-      GetFieldTrialParamByFeatureAsInt(kSchedUtilHints, "MinUrgent", 20);
-    uclamp_max_non_urgent = GetFieldTrialParamByFeatureAsInt(
-        kSchedUtilHints, "MaxNonUrgent", 100);
-    latency_sensitive_urgent = GetFieldTrialParamByFeatureAsBool(
-        kSchedUtilHints, "LatencySensitive", true);
+  if (g_scheduler_hints_adjusted.load()) {
+    uclamp_min_urgent = g_scheduler_boost_adj;
+    uclamp_max_non_urgent = g_scheduler_limit_adj;
+    latency_sensitive_urgent = g_scheduler_use_latency_tune_adj;
   } else {
-    // Use defaults if features were not parsed yet...
-    uclamp_min_urgent = 20;
-    uclamp_max_non_urgent = 100;
-    latency_sensitive_urgent = true;
+    uclamp_min_urgent = kSchedulerBoostDef;
+    uclamp_max_non_urgent = kSchedulerLimitDef;
+    latency_sensitive_urgent = kSchedulerUseLatencyTuneDef;
   }
 
   // The thread_id passed in here is either 0 (in which case we ste for current
@@ -369,8 +375,34 @@ void PlatformThread::InitThreadPostFieldTrial() {
   DCHECK(FeatureList::GetInstance());
   if (!FeatureList::IsEnabled(kSchedUtilHints)) {
     g_use_sched_util.store(false);
+    return;
   }
-  g_feature_checked.store(true);
+
+  int boost_def = kSchedulerBoostDef;
+
+  if (CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kSchedulerBoostUrgent)) {
+    std::string boost_switch_str =
+        CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+            switches::kSchedulerBoostUrgent);
+
+    int boost_switch_val;
+    if (!StringToInt(boost_switch_str, &boost_switch_val) ||
+        boost_switch_val < 0 || boost_switch_val > 100) {
+      DVPLOG(1) << "Invalid input for " << switches::kSchedulerBoostUrgent;
+    } else {
+      boost_def = boost_switch_val;
+    }
+  }
+
+  g_scheduler_boost_adj = GetFieldTrialParamByFeatureAsInt(
+      kSchedUtilHints, "BoostUrgent", boost_def);
+  g_scheduler_limit_adj = GetFieldTrialParamByFeatureAsInt(
+      kSchedUtilHints, "LimitNonUrgent", kSchedulerLimitDef);
+  g_scheduler_use_latency_tune_adj = GetFieldTrialParamByFeatureAsBool(
+      kSchedUtilHints, "LatencyTune", kSchedulerUseLatencyTuneDef);
+
+  g_scheduler_hints_adjusted.store(true);
 }
 #endif
 

chrome/browser/chromeos/login/chrome_restart_request.cc

@@ -129,6 +129,7 @@ void DeriveCommandLine(const GURL& start_url,
     ::switches::kPpapiInProcess,
     ::switches::kRemoteDebuggingPort,
     ::switches::kRendererStartupDialog,
+    ::switches::kSchedulerBoostUrgent,
     ::switches::kSchedulerConfigurationDefault,
     ::switches::kTouchDevices,
     ::switches::kTouchEventFeatureDetection,

content/browser/gpu/gpu_process_host.cc

@@ -305,6 +305,9 @@ static const char* const kSwitchNames[] = {
 #if BUILDFLAG(IS_CHROMEOS_ASH)
     switches::kPlatformDisallowsChromeOSDirectVideoDecoder,
 #endif
+#if BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS)
+    switches::kSchedulerBoostUrgent,
+#endif
 };
 
 // These values are persisted to logs. Entries should not be renumbered and

content/browser/renderer_host/render_process_host_impl.cc

@@ -3355,6 +3355,9 @@ void RenderProcessHostImpl::PropagateBrowserCommandLineToRenderer(
 #endif
 #if BUILDFLAG(ENABLE_PLATFORM_HEVC)
     switches::kEnableClearHevcForTesting,
+#endif
+#if BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS)
+    switches::kSchedulerBoostUrgent,
 #endif
   };
   renderer_cmd->CopySwitchesFrom(browser_cmd, kSwitchNames,

content/browser/utility_process_host.cc

@@ -287,6 +287,9 @@ bool UtilityProcessHost::StartProcess() {
       sandbox::policy::switches::kAddXrAppContainerCaps,
 #endif
       network::switches::kUseFirstPartySet,
+#if BUILDFLAG(IS_CHROMEOS_ASH) || BUILDFLAG(IS_CHROMEOS_LACROS)
+      switches::kSchedulerBoostUrgent,
+#endif
     };
     cmd_line->CopySwitchesFrom(browser_command_line, kSwitchNames,
                                base::size(kSwitchNames));