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1 /*
2  * Copyright (C) 2014 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 #pragma once
18 
19 #include <type_traits>
20 
21 #include "Configuration.h"
22 #include "FastThreadState.h"
23 
24 namespace android {
25 
26 // The FastThreadDumpState keeps a cache of FastThread statistics that can be logged by dumpsys.
27 // Each individual native word-sized field is accessed atomically.  But the
28 // overall structure is non-atomic, that is there may be an inconsistency between fields.
29 // No barriers or locks are used for either writing or reading.
30 // Only POD types are permitted, and the contents shouldn't be trusted (i.e. do range checks).
31 // It has a different lifetime than the FastThread, and so it can't be a member of FastThread.
32 struct FastThreadDumpState {
33     FastThreadDumpState();
34 
35     FastThreadState::Command mCommand = FastThreadState::INITIAL;  // current command
36     uint32_t mUnderruns = 0;        // total number of underruns
37     uint32_t mOverruns = 0;         // total number of overruns
38     struct timespec mMeasuredWarmupTs{};  // measured warmup time
39     uint32_t mWarmupCycles = 0;     // number of loop cycles required to warmup
40 
41 #ifdef FAST_THREAD_STATISTICS
42     // Recently collected samples of per-cycle monotonic time, thread CPU time, and CPU frequency.
43     // kSamplingN is max size of sampling frame (statistics), and must be a power of 2 <= 0x8000.
44     // The sample arrays are virtually allocated based on this compile-time constant,
45     // but are only initialized and used based on the runtime parameter mSamplingN.
46     static const uint32_t kSamplingN = 0x8000;
47     // Compile-time constant for a "low RAM device", must be a power of 2 <= kSamplingN.
48     // This value was chosen such that each array uses 1 small page (4 Kbytes).
49     static const uint32_t kSamplingNforLowRamDevice = 0x400;
50     // Corresponding runtime maximum size of sample arrays, must be a power of 2 <= kSamplingN.
51     uint32_t mSamplingN = 0;
52     // The bounds define the interval of valid samples, and are represented as follows:
53     //      newest open (excluded) endpoint   = lower 16 bits of bounds, modulo N
54     //      oldest closed (included) endpoint = upper 16 bits of bounds, modulo N
55     // Number of valid samples is newest - oldest.
56     uint32_t mBounds = 0;               // bounds for mMonotonicNs, mThreadCpuNs, and mCpukHz
57     // The elements in the *Ns arrays are in units of nanoseconds <= 3999999999.
58     uint32_t mMonotonicNs[kSamplingN];  // delta monotonic (wall clock) time
59     uint32_t mLoadNs[kSamplingN];       // delta CPU load in time
60 #ifdef CPU_FREQUENCY_STATISTICS
61     uint32_t mCpukHz[kSamplingN];       // absolute CPU clock frequency in kHz, bits 0-3 are CPU#
62 #endif
63 
64     // Increase sampling window after construction, must be a power of 2 <= kSamplingN
65     void    increaseSamplingN(uint32_t samplingN);
66 #endif
67 
68 };  // struct FastThreadDumpState
69 
70 // No virtuals.
71 static_assert(!std::is_polymorphic_v<FastThreadDumpState>);
72 
73 }  // namespace android
74