1 /*
2 * Copyright (C) 2018 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "src/traced/probes/ftrace/ftrace_data_source.h"
18
19 #include "src/traced/probes/ftrace/cpu_reader.h"
20 #include "src/traced/probes/ftrace/ftrace_controller.h"
21
22 #include "protos/perfetto/trace/ftrace/ftrace_event_bundle.pbzero.h"
23 #include "protos/perfetto/trace/ftrace/ftrace_stats.pbzero.h"
24 #include "protos/perfetto/trace/trace_packet.pbzero.h"
25
26 namespace perfetto {
27
28 // static
29 const ProbesDataSource::Descriptor FtraceDataSource::descriptor = {
30 /*name*/ "linux.ftrace",
31 /*flags*/ Descriptor::kFlagsNone,
32 };
33
FtraceDataSource(base::WeakPtr<FtraceController> controller_weak,TracingSessionID session_id,const FtraceConfig & config,std::unique_ptr<TraceWriter> writer)34 FtraceDataSource::FtraceDataSource(
35 base::WeakPtr<FtraceController> controller_weak,
36 TracingSessionID session_id,
37 const FtraceConfig& config,
38 std::unique_ptr<TraceWriter> writer)
39 : ProbesDataSource(session_id, &descriptor),
40 config_(config),
41 writer_(std::move(writer)),
42 controller_weak_(std::move(controller_weak)) {}
43
~FtraceDataSource()44 FtraceDataSource::~FtraceDataSource() {
45 if (controller_weak_)
46 controller_weak_->RemoveDataSource(this);
47 }
48
Initialize(FtraceConfigId config_id,const FtraceDataSourceConfig * parsing_config)49 void FtraceDataSource::Initialize(
50 FtraceConfigId config_id,
51 const FtraceDataSourceConfig* parsing_config) {
52 PERFETTO_CHECK(config_id);
53 config_id_ = config_id;
54 parsing_config_ = parsing_config;
55 }
56
Start()57 void FtraceDataSource::Start() {
58 FtraceController* ftrace = controller_weak_.get();
59 if (!ftrace)
60 return;
61 PERFETTO_CHECK(config_id_); // Must be initialized at this point.
62 if (!ftrace->StartDataSource(this))
63 return;
64 DumpFtraceStats(&stats_before_);
65 }
66
DumpFtraceStats(FtraceStats * stats)67 void FtraceDataSource::DumpFtraceStats(FtraceStats* stats) {
68 if (controller_weak_)
69 controller_weak_->DumpFtraceStats(stats);
70 }
71
Flush(FlushRequestID flush_request_id,std::function<void ()> callback)72 void FtraceDataSource::Flush(FlushRequestID flush_request_id,
73 std::function<void()> callback) {
74 if (!controller_weak_)
75 return;
76
77 pending_flushes_[flush_request_id] = std::move(callback);
78
79 // FtraceController will call OnFtraceFlushComplete() once the data has been
80 // drained from the ftrace buffer and written into the various writers of
81 // all its active data sources.
82 controller_weak_->Flush(flush_request_id);
83 }
84
85 // Called by FtraceController after all CPUs have acked the flush or timed out.
OnFtraceFlushComplete(FlushRequestID flush_request_id)86 void FtraceDataSource::OnFtraceFlushComplete(FlushRequestID flush_request_id) {
87 auto it = pending_flushes_.find(flush_request_id);
88 if (it == pending_flushes_.end()) {
89 // This can genuinely happen in case of concurrent ftrace sessions. When a
90 // FtraceDataSource issues a flush, the controller has to drain ftrace data
91 // for everybody (there is only one kernel ftrace buffer for all sessions).
92 // FtraceController doesn't bother to remember which FtraceDataSource did or
93 // did not request a flush. Instead just boradcasts the
94 // OnFtraceFlushComplete() to all of them.
95 return;
96 }
97 auto callback = std::move(it->second);
98 pending_flushes_.erase(it);
99 if (writer_) {
100 WriteStats();
101 writer_->Flush(std::move(callback));
102 }
103 }
104
WriteStats()105 void FtraceDataSource::WriteStats() {
106 {
107 auto before_packet = writer_->NewTracePacket();
108 auto out = before_packet->set_ftrace_stats();
109 out->set_phase(protos::pbzero::FtraceStats_Phase_START_OF_TRACE);
110 stats_before_.Write(out);
111 }
112 {
113 FtraceStats stats_after{};
114 DumpFtraceStats(&stats_after);
115 auto after_packet = writer_->NewTracePacket();
116 auto out = after_packet->set_ftrace_stats();
117 out->set_phase(protos::pbzero::FtraceStats_Phase_END_OF_TRACE);
118 stats_after.Write(out);
119 }
120 }
121
122 } // namespace perfetto
123