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Commit 0a14c4ce authored by Glenn Kasten's avatar Glenn Kasten
Browse files

Make CPU frequency statistics optional 

Certain CPUs with dynamic cluster swapping and hotplug
don't report CPU frequency accurately.  The file descriptors
used to read the frequency become stale and report bogus data.
So make this feature a build time option for debugging only.
This will also improve performance of the fast mixer loop.

Change-Id: I602f81ec3281a37992769208be08084ed1469e8c
parent 362ebcbf

services/audioflinger/Android.mk

+3 −0
Original line number Diff line number Diff line
@@ -84,6 +84,9 @@ LOCAL_SRC_FILES += FastMixer.cpp FastMixerState.cpp 


LOCAL_CFLAGS += -DFAST_MIXER_STATISTICS



# uncomment to display CPU load adjusted for CPU frequency

# LOCAL_CFLAGS += -DCPU_FREQUENCY_STATISTICS



LOCAL_CFLAGS += -DSTATE_QUEUE_INSTANTIATIONS='"StateQueueInstantiations.cpp"'



LOCAL_CFLAGS += -DHAVE_REQUEST_PRIORITY -UFAST_TRACKS_AT_NON_NATIVE_SAMPLE_RATE -USOAKER

services/audioflinger/FastMixer.cpp

+19 −4
Original line number Diff line number Diff line
@@ -24,8 +24,10 @@ 
#include <system/audio.h>

#ifdef FAST_MIXER_STATISTICS

#include <cpustats/CentralTendencyStatistics.h>

#ifdef CPU_FREQUENCY_STATISTICS

#include <cpustats/ThreadCpuUsage.h>

#endif

#endif

#include "AudioMixer.h"

#include "FastMixer.h"
@@ -71,7 +73,9 @@ bool FastMixer::threadLoop() 
    bool oldLoadValid = false;  // whether oldLoad is valid

    uint32_t bounds = 0;

    bool full = false;      // whether we have collected at least kSamplingN samples

#ifdef CPU_FREQUENCY_STATISTICS

    ThreadCpuUsage tcu;     // for reading the current CPU clock frequency in kHz

#endif

#endif

    unsigned coldGen = 0;   // last observed mColdGen

    bool isWarm = false;    // true means ready to mix, false means wait for warmup before mixing
@@ -527,16 +531,20 @@ bool FastMixer::threadLoop() 
                    }

                    oldLoad = newLoad;

                }

#ifdef CPU_FREQUENCY_STATISTICS

                // get the absolute value of CPU clock frequency in kHz

                int cpuNum = sched_getcpu();

                uint32_t kHz = tcu.getCpukHz(cpuNum);

                kHz = (kHz << 4) | (cpuNum & 0xF);

#endif

                // save values in FIFO queues for dumpsys

                // these stores #1, #2, #3 are not atomic with respect to each other,

                // or with respect to store #4 below

                dumpState->mMonotonicNs[i] = monotonicNs;

                dumpState->mLoadNs[i] = loadNs;

#ifdef CPU_FREQUENCY_STATISTICS

                dumpState->mCpukHz[i] = kHz;

#endif

                // this store #4 is not atomic with respect to stores #1, #2, #3 above, but

                // the newest open and oldest closed halves are atomic with respect to each other

                dumpState->mBounds = bounds;
@@ -579,7 +587,9 @@ FastMixerDumpState::FastMixerDumpState() : 
    // so clearing reduces chance for dumpsys to read random uninitialized samples

    memset(&mMonotonicNs, 0, sizeof(mMonotonicNs));

    memset(&mLoadNs, 0, sizeof(mLoadNs));

#ifdef CPU_FREQUENCY_STATISTICS

    memset(&mCpukHz, 0, sizeof(mCpukHz));

#endif

}



FastMixerDumpState::~FastMixerDumpState()
@@ -643,18 +653,20 @@ void FastMixerDumpState::dump(int fd) 
    }

    // statistics for monotonic (wall clock) time, thread raw CPU load in time, CPU clock frequency,

    // and adjusted CPU load in MHz normalized for CPU clock frequency

    CentralTendencyStatistics wall, loadNs, kHz, loadMHz;

    // only compute adjusted CPU load in Hz if current CPU number and CPU clock frequency are stable

    bool valid = false;

    CentralTendencyStatistics wall, loadNs;

#ifdef CPU_FREQUENCY_STATISTICS

    CentralTendencyStatistics kHz, loadMHz;

    uint32_t previousCpukHz = 0;

#endif

    // loop over all the samples

    for (; n > 0; --n) {

        size_t i = oldestClosed++ & (kSamplingN - 1);

        uint32_t wallNs = mMonotonicNs[i];

        wall.sample(wallNs);

        uint32_t sampleLoadNs = mLoadNs[i];

        uint32_t sampleCpukHz = mCpukHz[i];

        loadNs.sample(sampleLoadNs);

#ifdef CPU_FREQUENCY_STATISTICS

        uint32_t sampleCpukHz = mCpukHz[i];

        // skip bad kHz samples

        if ((sampleCpukHz & ~0xF) != 0) {

            kHz.sample(sampleCpukHz >> 4);
@@ -665,6 +677,7 @@ void FastMixerDumpState::dump(int fd) 
            }

        }

        previousCpukHz = sampleCpukHz;

#endif

    }

    fdprintf(fd, "Simple moving statistics over last %.1f seconds:\n", wall.n() * mixPeriodSec);

    fdprintf(fd, "  wall clock time in ms per mix cycle:\n"
@@ -674,12 +687,14 @@ void FastMixerDumpState::dump(int fd) 
                 "    mean=%.0f min=%.0f max=%.0f stddev=%.0f\n",

                 loadNs.mean()*1e-3, loadNs.minimum()*1e-3, loadNs.maximum()*1e-3,

                 loadNs.stddev()*1e-3);

#ifdef CPU_FREQUENCY_STATISTICS

    fdprintf(fd, "  CPU clock frequency in MHz:\n"

                 "    mean=%.0f min=%.0f max=%.0f stddev=%.0f\n",

                 kHz.mean()*1e-3, kHz.minimum()*1e-3, kHz.maximum()*1e-3, kHz.stddev()*1e-3);

    fdprintf(fd, "  adjusted CPU load in MHz (i.e. normalized for CPU clock frequency):\n"

                 "    mean=%.1f min=%.1f max=%.1f stddev=%.1f\n",

                 loadMHz.mean(), loadMHz.minimum(), loadMHz.maximum(), loadMHz.stddev());

#endif

#endif

    // The active track mask and track states are updated non-atomically.

    // So if we relied on isActive to decide whether to display,

services/audioflinger/FastMixer.h

+2 −0
Original line number Diff line number Diff line
@@ -116,8 +116,10 @@ struct FastMixerDumpState { 
    // The elements in the *Ns arrays are in units of nanoseconds <= 3999999999.

    uint32_t mMonotonicNs[kSamplingN];  // delta monotonic (wall clock) time

    uint32_t mLoadNs[kSamplingN];       // delta CPU load in time

#ifdef CPU_FREQUENCY_STATISTICS

    uint32_t mCpukHz[kSamplingN];       // absolute CPU clock frequency in kHz, bits 0-3 are CPU#

#endif

#endif

};



}   // namespace android