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 "perfetto/trace/ftrace/ftrace_event_bundle.pbzero.h"
23 #include "perfetto/trace/ftrace/ftrace_stats.pbzero.h"
24 #include "perfetto/trace/trace_packet.pbzero.h"
25
26 namespace perfetto {
27
28 // static
29 constexpr int FtraceDataSource::kTypeId;
30
FtraceDataSource(base::WeakPtr<FtraceController> controller_weak,TracingSessionID session_id,const FtraceConfig & config,std::unique_ptr<TraceWriter> writer)31 FtraceDataSource::FtraceDataSource(
32 base::WeakPtr<FtraceController> controller_weak,
33 TracingSessionID session_id,
34 const FtraceConfig& config,
35 std::unique_ptr<TraceWriter> writer)
36 : ProbesDataSource(session_id, kTypeId),
37 config_(config),
38 writer_(std::move(writer)),
39 controller_weak_(std::move(controller_weak)){};
40
~FtraceDataSource()41 FtraceDataSource::~FtraceDataSource() {
42 if (controller_weak_)
43 controller_weak_->RemoveDataSource(this);
44 };
45
Initialize(FtraceConfigId config_id,const EventFilter * event_filter)46 void FtraceDataSource::Initialize(FtraceConfigId config_id,
47 const EventFilter* event_filter) {
48 PERFETTO_CHECK(config_id);
49 config_id_ = config_id;
50 event_filter_ = event_filter;
51 }
52
Start()53 void FtraceDataSource::Start() {
54 FtraceController* ftrace = controller_weak_.get();
55 if (!ftrace)
56 return;
57 PERFETTO_CHECK(config_id_); // Must be initialized at this point.
58 if (!ftrace->StartDataSource(this))
59 return;
60 DumpFtraceStats(&stats_before_);
61 }
62
DumpFtraceStats(FtraceStats * stats)63 void FtraceDataSource::DumpFtraceStats(FtraceStats* stats) {
64 if (controller_weak_)
65 controller_weak_->DumpFtraceStats(stats);
66 }
67
Flush(FlushRequestID flush_request_id,std::function<void ()> callback)68 void FtraceDataSource::Flush(FlushRequestID flush_request_id,
69 std::function<void()> callback) {
70 if (!controller_weak_)
71 return;
72
73 pending_flushes_[flush_request_id] = std::move(callback);
74
75 // FtraceController will call OnFtraceFlushComplete() once the data has been
76 // drained from the ftrace buffer and written into the various writers of
77 // all its active data sources.
78 controller_weak_->Flush(flush_request_id);
79 }
80
81 // Called by FtraceController after all CPUs have acked the flush or timed out.
OnFtraceFlushComplete(FlushRequestID flush_request_id)82 void FtraceDataSource::OnFtraceFlushComplete(FlushRequestID flush_request_id) {
83 auto it = pending_flushes_.find(flush_request_id);
84 if (it == pending_flushes_.end()) {
85 // This can genuinely happen in case of concurrent ftrace sessions. When a
86 // FtraceDataSource issues a flush, the controller has to drain ftrace data
87 // for everybody (there is only one kernel ftrace buffer for all sessions).
88 // FtraceController doesn't bother to remember which FtraceDataSource did or
89 // did not request a flush. Instead just boradcasts the
90 // OnFtraceFlushComplete() to all of them.
91 return;
92 }
93 auto callback = std::move(it->second);
94 pending_flushes_.erase(it);
95 if (writer_) {
96 WriteStats();
97 writer_->Flush(std::move(callback));
98 }
99 }
100
WriteStats()101 void FtraceDataSource::WriteStats() {
102 {
103 auto before_packet = writer_->NewTracePacket();
104 auto out = before_packet->set_ftrace_stats();
105 out->set_phase(protos::pbzero::FtraceStats_Phase_START_OF_TRACE);
106 stats_before_.Write(out);
107 }
108 {
109 FtraceStats stats_after{};
110 DumpFtraceStats(&stats_after);
111 auto after_packet = writer_->NewTracePacket();
112 auto out = after_packet->set_ftrace_stats();
113 out->set_phase(protos::pbzero::FtraceStats_Phase_END_OF_TRACE);
114 stats_after.Write(out);
115 }
116 }
117
118 } // namespace perfetto
119