protos/perfetto/config/ftrace/ftrace_config.proto

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

syntax = "proto2";

package perfetto.protos;

// Next id: 29
message FtraceConfig {
  // Ftrace events to record, example: "sched/sched_switch".
  repeated string ftrace_events = 1;
  // Android-specific event categories:
  repeated string atrace_categories = 2;
  repeated string atrace_apps = 3;
  // Some processes can emit data through atrace or through the perfetto SDK via
  // the "track_event" data source. For these categories, the SDK will be
  // preferred, if possible, for this config.
  repeated string atrace_categories_prefer_sdk = 28;

  // Size of each per-cpu kernel ftrace ring buffer.
  // Not guaranteed if there are multiple concurrent tracing sessions, as the
  // buffers cannot be resized without pausing recording in the kernel.
  optional uint32 buffer_size_kb = 10;

  // If set, specifies how often the tracing daemon reads from the kernel ring
  // buffer. Not guaranteed if there are multiple concurrent tracing sessions.
  // Leave unset unless you're fine-tuning a local config.
  optional uint32 drain_period_ms = 11;

  // If set, the tracing daemon will read kernel ring buffers as soon as
  // they're filled past this percentage of occupancy. In other words, a value
  // of 50 means that a read pass is triggered as soon as any per-cpu buffer is
  // half-full. Not guaranteed if there are multiple concurrent tracing
  // sessions.
  // Currently does nothing on Linux kernels below v6.1.
  // Introduced in: perfetto v43.
  optional uint32 drain_buffer_percent = 26;

  // Configuration for compact encoding of scheduler events. When enabled (and
  // recording the relevant ftrace events), specific high-volume events are
  // encoded in a denser format than normal.
  message CompactSchedConfig {
    // If true, and sched_switch or sched_waking ftrace events are enabled,
    // record those events in the compact format.
    //
    // If the field is unset, the default is:
    // * perfetto v42.0+: enabled
    // * before: disabled
    optional bool enabled = 1;
  }
  optional CompactSchedConfig compact_sched = 12;

  // Optional filter for "ftrace/print" events.
  //
  // The filter consists of multiple rules. As soon as a rule matches (the rules
  // are processed in order), its `allow` field will be used as the outcome: if
  // `allow` is true, the event will be included in the trace, otherwise it will
  // be discarded. If an event does not match any rule, it will be allowed by
  // default (a rule with an empty prefix and allow=false, disallows everything
  // by default).
  message PrintFilter {
    message Rule {
      // Matches an atrace message of the form:
      // <type>|pid|<prefix>...
      message AtraceMessage {
        optional string type = 1;
        optional string prefix = 2;
      }
      oneof match {
        // This rule matches if `prefix` matches exactly with the beginning of
        // the "ftrace/print" "buf" field.
        string prefix = 1;
        // This rule matches if the "buf" field contains an atrace-style print
        // message as specified in `atrace_msg`.
        AtraceMessage atrace_msg = 3;
      }
      optional bool allow = 2;
    }
    repeated Rule rules = 1;
  }
  optional PrintFilter print_filter = 22;

  // Enables symbol name resolution against /proc/kallsyms.
  // It requires that either traced_probes is running as root or that
  // kptr_restrict has been manually lowered.
  // It does not disclose KASLR, symbol addresses are mangled.
  optional bool symbolize_ksyms = 13;

  // When symbolize_ksyms=true, determines whether the traced_probes daemon
  // should keep the symbol map in memory (and reuse it for future tracing
  // sessions) or clear it (saving memory) and re-create it on each tracing
  // session (wasting cpu and wall time).
  // The tradeoff is roughly:
  //  KSYMS_RETAIN: pay a fixed ~1.2 MB cost after the first trace.
  //  KSYMS_CLEANUP_ON_STOP: pay a ~300-500ms cost when starting each trace.
  // Default behavior: KSYMS_CLEANUP_ON_STOP.
  enum KsymsMemPolicy {
    KSYMS_UNSPECIFIED = 0;
    KSYMS_CLEANUP_ON_STOP = 1;
    KSYMS_RETAIN = 2;
  }
  optional KsymsMemPolicy ksyms_mem_policy = 17;

  // By default the kernel symbolizer is lazily initialized on a deferred task
  // to reduce ftrace's time-to-start-recording. Unfortunately that makes
  // ksyms integration tests hard. This flag forces the kernel symbolizer to be
  // initialized synchronously on the data source start and hence avoiding
  // timing races in tests.
  // DEPRECATED in v28 / Android U. This is now the default behavior, setting it
  // to true is a no-op.
  optional bool initialize_ksyms_synchronously_for_testing = 14
      [deprecated = true];

  // When this boolean is true AND the ftrace_events contains "kmem/rss_stat",
  // this option causes traced_probes to enable the "kmem/rss_stat_throttled"
  // event instead if present, and fall back to "kmem/rss_stat" if not present.
  // The historical context for this is the following:
  // - Up to Android S (12), the rss_stat was internally throttled in its
  //   kernel implementation.
  // - A change introduced in the kernels after S has introduced a new
  //   "rss_stat_throttled" making the original "rss_stat" event unthrottled
  //   (hence very spammy).
  // - Not all Android T/13 devices will receive a new kernel though, hence we
  //   need to deal with both cases.
  // For more context: go/rss-stat-throttled.
  optional bool throttle_rss_stat = 15;

  // If true, avoid enabling events that aren't statically known by
  // traced_probes. Otherwise, the default is to emit such events as
  // GenericFtraceEvent protos.
  // Prefer to keep this flag at its default. This was added for Android
  // tracing, where atrace categories and/or atrace HAL requested events can
  // expand to events that aren't of interest to the tracing user.
  // Introduced in: Android T.
  optional bool disable_generic_events = 16;

  // The subset of syscalls to record. To record all syscalls, leave this unset
  // and add "ftrace_events: raw_syscalls/sys_{enter,exit}" to the config.
  // * before perfetto v43, requires the config to also enable
  //   raw_syscalls/sys_{enter,exit}.
  // * perfetto v43+ does the right thing if you set only this field.
  // Example: ["sys_read", "sys_open"].
  // Introduced in: Android U.
  repeated string syscall_events = 18;

  // If true, enable the "function_graph" kernel tracer that emits events
  // whenever a kernel function is entered and exited
  // (funcgraph_entry/funcgraph_exit).
  // Notes on use:
  // * Requires |symbolize_ksyms| for function name resolution.
  // * Use |function_filters| or |function_graph_roots| to constrain the traced
  //   set of functions, otherwise the event bandwidth will be too high for
  //   practical use.
  // * The data source might be rejected if there is already a concurrent
  //   ftrace data source that does not use function graph itself, as we do not
  //   support switching kernel tracers mid-trace.
  // * Requires a kernel compiled with CONFIG_FUNCTION_GRAPH_TRACER. This is
  //   enabled if "cat /sys/kernel/tracing/available_tracers" includes
  //   "function_graph".
  // Android:
  // * Available only on debuggable builds.
  // * Introduced in: Android U.
  optional bool enable_function_graph = 19;

  // Constrains the set of functions traced when |enable_function_graph| is
  // true. Supports globs, e.g. "sched*". You can specify multiple filters,
  // in which case all matching functions will be traced. See kernel
  // documentation on ftrace "set_ftrace_filter" file for more details.
  // Android:
  // * Available only on debuggable builds.
  // * Introduced in: Android U.
  repeated string function_filters = 20;

  // If |enable_function_graph| is true, trace this set of functions *and* all
  // of its callees. Supports globs. Can be set together with
  // |function_filters|, in which case only callees matching the filter will be
  // traced. If setting both, you most likely want all roots to also be
  // included in |function_filters|.
  // Android:
  // * Available only on debuggable builds.
  // * Introduced in: Android U.
  repeated string function_graph_roots = 21;

  // If true, does not clear ftrace buffers before the start of the program.
  // This makes sense only if this is the first ftrace data source instance
  // created after the daemon has been started. Can be useful for gathering boot
  // traces, if ftrace has been separately configured (e.g. via kernel
  // commandline).
  optional bool preserve_ftrace_buffer = 23;

  // If true, overrides the default timestamp clock and uses a raw hardware
  // based monotonic clock for getting timestamps.
  // * Introduced in: Android U.
  optional bool use_monotonic_raw_clock = 24;

  // If |instance_name| is not empty, then attempt to use that tracefs instance
  // for event recording. Normally, this means
  // `/sys/kernel/tracing/instances/$instance_name`.
  //
  // The name "hyp" is reserved.
  //
  // The instance must already exist, the tracing daemon *will not* create it
  // for you as it typically doesn't have such permissions.
  // Only a subset of features is guaranteed to work with non-default instances,
  // at the time of writing:
  //  * ftrace_events
  //  * buffer_size_kb
  optional string instance_name = 25;

  // If true, |buffer_size_kb| is interpreted as a lower bound, allowing the
  // implementation to choose a bigger buffer size.
  //
  // Most configs for perfetto v43+ should simply leave both fields unset.
  //
  // If you need a config compatible with a range of perfetto builds and you
  // used to set a non-default buffer_size_kb, consider setting both fields.
  // Example:
  //   buffer_size_kb: 4096
  //   buffer_size_lower_bound: true
  // On older builds, the per-cpu buffers will be exactly 4 MB.
  // On v43+, buffers will be at least 4 MB.
  // In both cases, neither is guaranteed if there are other concurrent
  // perfetto ftrace sessions, as the buffers cannot be resized without pausing
  // the recording in the kernel.
  // Introduced in: perfetto v43.
  optional bool buffer_size_lower_bound = 27;
}