Merge atrace/ from platform/system/extras to cmds/atrace/

4 files changed, 850 insertions, 0 deletions

diff --git a/cmds/atrace/Android.mk b/cmds/atrace/Android.mk
new file mode 100644
index 0000000000..12526d0235
--- /dev/null
+++ b/cmds/atrace/Android.mk
@@ -0,0 +1,17 @@
+# Copyright 2012 The Android Open Source Project
+
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES:= atrace.c
+
+LOCAL_C_INCLUDES += external/zlib
+LOCAL_CFLAGS += -std=c99
+
+LOCAL_MODULE:= atrace
+
+LOCAL_MODULE_TAGS:= optional
+
+LOCAL_SHARED_LIBRARIES := libz
+
+include $(BUILD_EXECUTABLE)
diff --git a/cmds/atrace/MODULE_LICENSE_APACHE2 b/cmds/atrace/MODULE_LICENSE_APACHE2
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/cmds/atrace/MODULE_LICENSE_APACHE2
diff --git a/cmds/atrace/NOTICE b/cmds/atrace/NOTICE
new file mode 100644
index 0000000000..c77f135e76
--- /dev/null
+++ b/cmds/atrace/NOTICE
@@ -0,0 +1,190 @@
+
+   Copyright (c) 2012, 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.
+
+   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.
+
+
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
diff --git a/cmds/atrace/atrace.c b/cmds/atrace/atrace.c
new file mode 100644
index 0000000000..64f13e4eb5
--- /dev/null
+++ b/cmds/atrace/atrace.c
@@ -0,0 +1,643 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/sendfile.h>
+#include <time.h>
+#include <zlib.h>
+
+#define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))
+
+/* Command line options */
+static int g_traceDurationSeconds = 5;
+static bool g_traceSchedSwitch = false;
+static bool g_traceFrequency = false;
+static bool g_traceBusUtilization = false;
+static bool g_traceCpuIdle = false;
+static bool g_traceDisk = false;
+static bool g_traceGovernorLoad = false;
+static bool g_traceSync = false;
+static bool g_traceWorkqueue = false;
+static bool g_traceOverwrite = false;
+static int g_traceBufferSizeKB = 2048;
+static bool g_compress = false;
+static bool g_nohup = false;
+static int g_initialSleepSecs = 0;
+
+/* Global state */
+static bool g_traceAborted = false;
+
+/* Sys file paths */
+static const char* k_traceClockPath =
+    "/sys/kernel/debug/tracing/trace_clock";
+
+static const char* k_traceBufferSizePath =
+    "/sys/kernel/debug/tracing/buffer_size_kb";
+
+static const char* k_tracingOverwriteEnablePath =
+    "/sys/kernel/debug/tracing/options/overwrite";
+
+static const char* k_schedSwitchEnablePath =
+    "/sys/kernel/debug/tracing/events/sched/sched_switch/enable";
+
+static const char* k_schedWakeupEnablePath =
+    "/sys/kernel/debug/tracing/events/sched/sched_wakeup/enable";
+
+static const char* k_memoryBusEnablePath =
+    "/sys/kernel/debug/tracing/events/memory_bus/enable";
+
+static const char* k_cpuFreqEnablePath =
+    "/sys/kernel/debug/tracing/events/power/cpu_frequency/enable";
+
+static const char *k_clockSetRateEnablePath =
+    "/sys/kernel/debug/tracing/events/power/clock_set_rate/enable";
+
+static const char* k_cpuIdleEnablePath =
+    "/sys/kernel/debug/tracing/events/power/cpu_idle/enable";
+
+static const char* k_governorLoadEnablePath =
+    "/sys/kernel/debug/tracing/events/cpufreq_interactive/enable";
+
+static const char* k_syncEnablePath =
+    "/sys/kernel/debug/tracing/events/sync/enable";
+
+static const char* k_workqueueEnablePath =
+    "/sys/kernel/debug/tracing/events/workqueue/enable";
+
+static const char* k_diskEnablePaths[] = {
+        "/sys/kernel/debug/tracing/events/ext4/ext4_sync_file_enter/enable",
+        "/sys/kernel/debug/tracing/events/ext4/ext4_sync_file_exit/enable",
+        "/sys/kernel/debug/tracing/events/block/block_rq_issue/enable",
+        "/sys/kernel/debug/tracing/events/block/block_rq_complete/enable",
+};
+
+static const char* k_tracingOnPath =
+    "/sys/kernel/debug/tracing/tracing_on";
+
+static const char* k_tracePath =
+    "/sys/kernel/debug/tracing/trace";
+
+static const char* k_traceMarkerPath =
+    "/sys/kernel/debug/tracing/trace_marker";
+
+// Check whether a file exists.
+static bool fileExists(const char* filename) {
+    return access(filename, F_OK) != -1;
+}
+
+// Write a string to a file, returning true if the write was successful.
+bool writeStr(const char* filename, const char* str)
+{
+    int fd = open(filename, O_WRONLY);
+    if (fd == -1) {
+        fprintf(stderr, "error opening %s: %s (%d)\n", filename,
+                strerror(errno), errno);
+        return false;
+    }
+
+    bool ok = true;
+    ssize_t len = strlen(str);
+    if (write(fd, str, len) != len) {
+        fprintf(stderr, "error writing to %s: %s (%d)\n", filename,
+                strerror(errno), errno);
+        ok = false;
+    }
+
+    close(fd);
+
+    return ok;
+}
+
+// Enable or disable a kernel option by writing a "1" or a "0" into a /sys file.
+static bool setKernelOptionEnable(const char* filename, bool enable)
+{
+    return writeStr(filename, enable ? "1" : "0");
+}
+
+// Enable or disable a collection of kernel options by writing a "1" or a "0" into each /sys file.
+static bool setMultipleKernelOptionsEnable(const char** filenames, size_t count, bool enable)
+{
+    bool result = true;
+    for (size_t i = 0; i < count; i++) {
+        result &= setKernelOptionEnable(filenames[i], enable);
+    }
+    return result;
+}
+
+// Enable or disable overwriting of the kernel trace buffers.  Disabling this
+// will cause tracing to stop once the trace buffers have filled up.
+static bool setTraceOverwriteEnable(bool enable)
+{
+    return setKernelOptionEnable(k_tracingOverwriteEnablePath, enable);
+}
+
+// Enable or disable tracing of the kernel scheduler switching.
+static bool setSchedSwitchTracingEnable(bool enable)
+{
+    bool ok = true;
+    ok &= setKernelOptionEnable(k_schedSwitchEnablePath, enable);
+    ok &= setKernelOptionEnable(k_schedWakeupEnablePath, enable);
+    return ok;
+}
+
+// Enable or disable tracing of the Bus utilization.
+static bool setBusUtilizationTracingEnable(bool enable)
+{
+    bool ok = true, oneSet = false;
+    // these can be platform specific so make sure that at least
+    // one succeeds.
+    if (fileExists(k_memoryBusEnablePath)) {
+        ok &= setKernelOptionEnable(k_memoryBusEnablePath, enable);
+        oneSet |= ok;
+    }
+    return ok && (oneSet || !enable);
+}
+
+// Enable or disable tracing of the CPU clock frequency.
+static bool setFrequencyTracingEnable(bool enable)
+{
+    bool ok = true;
+    ok &= setKernelOptionEnable(k_cpuFreqEnablePath, enable);
+    if (fileExists(k_clockSetRateEnablePath)) {
+        ok &= setKernelOptionEnable(k_clockSetRateEnablePath, enable);
+    }
+    return ok;
+}
+
+// Enable or disable tracing of CPU idle events.
+static bool setCpuIdleTracingEnable(bool enable)
+{
+    return setKernelOptionEnable(k_cpuIdleEnablePath, enable);
+}
+
+// Enable or disable tracing of the interactive CPU frequency governor's idea of
+// the CPU load.
+static bool setGovernorLoadTracingEnable(bool enable)
+{
+    bool ok = true;
+    if (fileExists(k_governorLoadEnablePath) || enable) {
+        ok &= setKernelOptionEnable(k_governorLoadEnablePath, enable);
+    }
+    return ok;
+}
+
+// Enable or disable tracing of sync timelines and waits.
+static bool setSyncTracingEnabled(bool enable)
+{
+    bool ok = true;
+    if (fileExists(k_syncEnablePath) || enable) {
+        ok &= setKernelOptionEnable(k_syncEnablePath, enable);
+    }
+    return ok;
+}
+
+// Enable or disable tracing of the kernel workqueues.
+static bool setWorkqueueTracingEnabled(bool enable)
+{
+    return setKernelOptionEnable(k_workqueueEnablePath, enable);
+}
+
+// Enable or disable tracing of disk I/O.
+static bool setDiskTracingEnabled(bool enable)
+{
+    return setMultipleKernelOptionsEnable(k_diskEnablePaths, NELEM(k_diskEnablePaths), enable);
+}
+
+// Enable or disable kernel tracing.
+static bool setTracingEnabled(bool enable)
+{
+    return setKernelOptionEnable(k_tracingOnPath, enable);
+}
+
+// Clear the contents of the kernel trace.
+static bool clearTrace()
+{
+    int traceFD = creat(k_tracePath, 0);
+    if (traceFD == -1) {
+        fprintf(stderr, "error truncating %s: %s (%d)\n", k_tracePath,
+                strerror(errno), errno);
+        return false;
+    }
+
+    close(traceFD);
+
+    return true;
+}
+
+// Set the size of the kernel's trace buffer in kilobytes.
+static bool setTraceBufferSizeKB(int size)
+{
+    char str[32] = "1";
+    int len;
+    if (size < 1) {
+        size = 1;
+    }
+    snprintf(str, 32, "%d", size);
+    return writeStr(k_traceBufferSizePath, str);
+}
+
+// Enable or disable the kernel's use of the global clock.  Disabling the global
+// clock will result in the kernel using a per-CPU local clock.
+static bool setGlobalClockEnable(bool enable)
+{
+    return writeStr(k_traceClockPath, enable ? "global" : "local");
+}
+
+// Enable tracing in the kernel.
+static bool startTrace(bool isRoot)
+{
+    bool ok = true;
+
+    // Set up the tracing options that don't require root.
+    ok &= setTraceOverwriteEnable(g_traceOverwrite);
+    ok &= setSchedSwitchTracingEnable(g_traceSchedSwitch);
+    ok &= setFrequencyTracingEnable(g_traceFrequency);
+    ok &= setCpuIdleTracingEnable(g_traceCpuIdle);
+    ok &= setGovernorLoadTracingEnable(g_traceGovernorLoad);
+    ok &= setTraceBufferSizeKB(g_traceBufferSizeKB);
+    ok &= setGlobalClockEnable(true);
+
+    // Set up the tracing options that do require root.  The options that
+    // require root should have errored out earlier if we're not running as
+    // root.
+    if (isRoot) {
+        ok &= setBusUtilizationTracingEnable(g_traceBusUtilization);
+        ok &= setSyncTracingEnabled(g_traceSync);
+        ok &= setWorkqueueTracingEnabled(g_traceWorkqueue);
+        ok &= setDiskTracingEnabled(g_traceDisk);
+    }
+
+    // Enable tracing.
+    ok &= setTracingEnabled(true);
+
+    if (!ok) {
+        fprintf(stderr, "error: unable to start trace\n");
+    }
+
+    return ok;
+}
+
+// Disable tracing in the kernel.
+static void stopTrace(bool isRoot)
+{
+    // Disable tracing.
+    setTracingEnabled(false);
+
+    // Set the options back to their defaults.
+    setTraceOverwriteEnable(true);
+    setSchedSwitchTracingEnable(false);
+    setFrequencyTracingEnable(false);
+    setGovernorLoadTracingEnable(false);
+    setGlobalClockEnable(false);
+
+    if (isRoot) {
+        setBusUtilizationTracingEnable(false);
+        setSyncTracingEnabled(false);
+        setWorkqueueTracingEnabled(false);
+        setDiskTracingEnabled(false);
+    }
+
+    // Note that we can't reset the trace buffer size here because that would
+    // clear the trace before we've read it.
+}
+
+// Read the current kernel trace and write it to stdout.
+static void dumpTrace()
+{
+    int traceFD = open(k_tracePath, O_RDWR);
+    if (traceFD == -1) {
+        fprintf(stderr, "error opening %s: %s (%d)\n", k_tracePath,
+                strerror(errno), errno);
+        return;
+    }
+
+    if (g_compress) {
+        z_stream zs;
+        uint8_t *in, *out;
+        int result, flush;
+
+        bzero(&zs, sizeof(zs));
+        result = deflateInit(&zs, Z_DEFAULT_COMPRESSION);
+        if (result != Z_OK) {
+            fprintf(stderr, "error initializing zlib: %d\n", result);
+            close(traceFD);
+            return;
+        }
+
+        const size_t bufSize = 64*1024;
+        in = (uint8_t*)malloc(bufSize);
+        out = (uint8_t*)malloc(bufSize);
+        flush = Z_NO_FLUSH;
+
+        zs.next_out = out;
+        zs.avail_out = bufSize;
+
+        do {
+
+            if (zs.avail_in == 0) {
+                // More input is needed.
+                result = read(traceFD, in, bufSize);
+                if (result < 0) {
+                    fprintf(stderr, "error reading trace: %s (%d)\n",
+                            strerror(errno), errno);
+                    result = Z_STREAM_END;
+                    break;
+                } else if (result == 0) {
+                    flush = Z_FINISH;
+                } else {
+                    zs.next_in = in;
+                    zs.avail_in = result;
+                }
+            }
+
+            if (zs.avail_out == 0) {
+                // Need to write the output.
+                result = write(STDOUT_FILENO, out, bufSize);
+                if ((size_t)result < bufSize) {
+                    fprintf(stderr, "error writing deflated trace: %s (%d)\n",
+                            strerror(errno), errno);
+                    result = Z_STREAM_END; // skip deflate error message
+                    zs.avail_out = bufSize; // skip the final write
+                    break;
+                }
+                zs.next_out = out;
+                zs.avail_out = bufSize;
+            }
+
+        } while ((result = deflate(&zs, flush)) == Z_OK);
+
+        if (result != Z_STREAM_END) {
+            fprintf(stderr, "error deflating trace: %s\n", zs.msg);
+        }
+
+        if (zs.avail_out < bufSize) {
+            size_t bytes = bufSize - zs.avail_out;
+            result = write(STDOUT_FILENO, out, bytes);
+            if ((size_t)result < bytes) {
+                fprintf(stderr, "error writing deflated trace: %s (%d)\n",
+                        strerror(errno), errno);
+            }
+        }
+
+        result = deflateEnd(&zs);
+        if (result != Z_OK) {
+            fprintf(stderr, "error cleaning up zlib: %d\n", result);
+        }
+
+        free(in);
+        free(out);
+    } else {
+        ssize_t sent = 0;
+        while ((sent = sendfile(STDOUT_FILENO, traceFD, NULL, 64*1024*1024)) > 0);
+        if (sent == -1) {
+            fprintf(stderr, "error dumping trace: %s (%d)\n", strerror(errno),
+                    errno);
+        }
+    }
+
+    close(traceFD);
+}
+
+// Print the command usage help to stderr.
+static void showHelp(const char *cmd)
+{
+    fprintf(stderr, "usage: %s [options]\n", cmd);
+    fprintf(stderr, "options include:\n"
+                    "  -b N            use a trace buffer size of N KB\n"
+                    "  -c              trace into a circular buffer\n"
+                    "  -d              trace disk I/O\n"
+                    "  -f              trace clock frequency changes\n"
+                    "  -l              trace CPU frequency governor load\n"
+                    "  -s              trace the kernel scheduler switches\n"
+                    "  -t N            trace for N seconds [defualt 5]\n"
+                    "  -u              trace bus utilization\n"
+                    "  -w              trace the kernel workqueue\n"
+                    "  -y              trace sync timelines and waits\n"
+                    "  -z              compress the trace dump\n"
+                    "  --async_start   start circular trace and return immediatly\n"
+                    "  --async_dump    dump the current contents of circular trace buffer\n"
+                    "  --async_stop    stop tracing and dump the current contents of circular\n"
+                    "                    trace buffer\n"
+            );
+}
+
+static void handleSignal(int signo) {
+    if (!g_nohup) {
+        g_traceAborted = true;
+    }
+}
+
+static void registerSigHandler() {
+    struct sigaction sa;
+    sigemptyset(&sa.sa_mask);
+    sa.sa_flags = 0;
+    sa.sa_handler = handleSignal;
+    sigaction(SIGHUP, &sa, NULL);
+    sigaction(SIGINT, &sa, NULL);
+    sigaction(SIGQUIT, &sa, NULL);
+    sigaction(SIGTERM, &sa, NULL);
+}
+
+int main(int argc, char **argv)
+{
+    bool isRoot = (getuid() == 0);
+    bool async = false;
+    bool traceStart = true;
+    bool traceStop = true;
+    bool traceDump = true;
+
+    if (argc == 2 && 0 == strcmp(argv[1], "--help")) {
+        showHelp(argv[0]);
+        exit(0);
+    }
+
+    for (;;) {
+        int ret;
+        int option_index = 0;
+        static struct option long_options[] = {
+            {"async_start",     no_argument, 0,  0 },
+            {"async_stop",      no_argument, 0,  0 },
+            {"async_dump",      no_argument, 0,  0 },
+            {0,         0,                 0,  0 }
+        };
+
+        ret = getopt_long(argc, argv, "b:cidflst:uwyznS:",
+                          long_options, &option_index);
+
+        if (ret < 0) {
+            break;
+        }
+
+        switch(ret) {
+            case 'b':
+                g_traceBufferSizeKB = atoi(optarg);
+            break;
+
+            case 'c':
+                g_traceOverwrite = true;
+            break;
+
+            case 'i':
+                g_traceCpuIdle = true;
+            break;
+
+            case 'l':
+                g_traceGovernorLoad = true;
+            break;
+
+            case 'd':
+                if (!isRoot) {
+                    fprintf(stderr, "error: tracing disk activity requires root privileges\n");
+                    exit(1);
+                }
+                g_traceDisk = true;
+            break;
+
+            case 'f':
+                g_traceFrequency = true;
+            break;
+
+            case 'n':
+                g_nohup = true;
+                break;
+
+            case 's':
+                g_traceSchedSwitch = true;
+            break;
+
+            case 'S':
+                g_initialSleepSecs = atoi(optarg);
+            break;
+
+            case 't':
+                g_traceDurationSeconds = atoi(optarg);
+            break;
+
+            case 'u':
+                if (!isRoot) {
+                    fprintf(stderr, "error: tracing bus utilization requires root privileges\n");
+                    exit(1);
+                }
+                g_traceBusUtilization = true;
+            break;
+
+            case 'w':
+                if (!isRoot) {
+                    fprintf(stderr, "error: tracing kernel work queues requires root privileges\n");
+                    exit(1);
+                }
+                g_traceWorkqueue = true;
+            break;
+
+            case 'y':
+                if (!isRoot) {
+                    fprintf(stderr, "error: tracing sync requires root privileges\n");
+                    exit(1);
+                }
+                g_traceSync = true;
+            break;
+
+            case 'z':
+                g_compress = true;
+            break;
+
+            case 0:
+                if (!strcmp(long_options[option_index].name, "async_start")) {
+                    async = true;
+                    traceStop = false;
+                    traceDump = false;
+                    g_traceOverwrite = true;
+                } else if (!strcmp(long_options[option_index].name, "async_stop")) {
+                    async = true;
+                    traceStop = false;
+                } else if (!strcmp(long_options[option_index].name, "async_dump")) {
+                    async = true;
+                    traceStart = false;
+                    traceStop = false;
+                }
+                break;
+
+            default:
+                fprintf(stderr, "\n");
+                showHelp(argv[0]);
+                exit(-1);
+            break;
+        }
+    }
+
+    registerSigHandler();
+
+    if (g_initialSleepSecs > 0) {
+        sleep(g_initialSleepSecs);
+    }
+
+    bool ok = startTrace(isRoot);
+
+    if (ok && traceStart) {
+        printf("capturing trace...");
+        fflush(stdout);
+
+        // We clear the trace after starting it because tracing gets enabled for
+        // each CPU individually in the kernel. Having the beginning of the trace
+        // contain entries from only one CPU can cause "begin" entries without a
+        // matching "end" entry to show up if a task gets migrated from one CPU to
+        // another.
+        ok = clearTrace();
+
+        if (ok && !async) {
+            // Sleep to allow the trace to be captured.
+            struct timespec timeLeft;
+            timeLeft.tv_sec = g_traceDurationSeconds;
+            timeLeft.tv_nsec = 0;
+            do {
+                if (g_traceAborted) {
+                    break;
+                }
+            } while (nanosleep(&timeLeft, &timeLeft) == -1 && errno == EINTR);
+        }
+    }
+
+    // Stop the trace and restore the default settings.
+    if (traceStop)
+        stopTrace(isRoot);
+
+    if (ok && traceDump) {
+        if (!g_traceAborted) {
+            printf(" done\nTRACE:\n");
+            fflush(stdout);
+            dumpTrace();
+        } else {
+            printf("\ntrace aborted.\n");
+            fflush(stdout);
+        }
+        clearTrace();
+    } else if (!ok) {
+        fprintf(stderr, "unable to start tracing\n");
+    }
+
+    // Reset the trace buffer size to 1.
+    if (traceStop)
+        setTraceBufferSizeKB(1);
+
+    return g_traceAborted ? 1 : 0;
+}