common/options/crimson: introduce crimson_poll_mode

We shoudn't expect real deployments to enable this options (though
it might be useful for some). Enabling poll mode could provide further
insights on performance "potential" and help with discovering
bottlenecks.

Signed-off-by: Matan Breizman <[email protected]>

Author: Matan-B

src/common/options/crimson.yaml.in

@@ -85,6 +85,17 @@ options:
   level: advanced
   default: 0
   desc: Report OSD status periodically in seconds, 0 to disable
+
+- name: crimson_poll_mode
+  type: bool
+  level: advanced
+  default: false
+  desc: Let the seastar reactor poll continuously without sleeping at the expense of 100% cpu usage.
+  flags:
+  - startup
+
+# Seastore options
+
 - name: seastore_segment_size
   type: size
   desc: Segment size to use for SegmentManager

src/crimson/osd/main_config_bootstrap_helpers.cc

@@ -95,7 +95,8 @@ struct SeastarOption {
 const std::vector<SeastarOption> seastar_options = {
   {"--task-quota-ms", "crimson_reactor_task_quota_ms", Option::TYPE_FLOAT},
   {"--io-latency-goal-ms", "crimson_reactor_io_latency_goal_ms", Option::TYPE_FLOAT},
-  {"--idle-poll-time-us", "crimson_reactor_idle_poll_time_us", Option::TYPE_UINT}
+  {"--idle-poll-time-us", "crimson_reactor_idle_poll_time_us", Option::TYPE_UINT},
+  {"--poll-mode", "crimson_poll_mode", Option::TYPE_BOOL}
 };
 
 // Function to get the option value as a string
@@ -113,6 +114,12 @@ std::optional<std::string> get_option_value(const SeastarOption& option) {
       }
       break;
     }
+    case Option::TYPE_BOOL: {
+     if (crimson::common::get_conf<bool>(option.config_key)) {
+        return "true";
+      }
+      break;
+    }
     default:
       logger().warn("get_option_value --option_name {} encountered unknown type", option.config_key);
       return std::nullopt;
@@ -184,7 +191,9 @@ _get_early_config(int argc, const char *argv[])
           if (option_value) {
             logger().info("Configure option_name {} with value : {}", option.config_key, option_value);
             ret.early_args.emplace_back(option.option_name);
-            ret.early_args.emplace_back(*option_value);
+            if (option.value_type != Option::TYPE_BOOL) {
+              ret.early_args.emplace_back(*option_value);
+            }
           }
         }
 	if (auto found = std::find_if(