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libsysprof: setup perf streams in prepare

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This starts the perf streams from prepare instead of from record so that
we can do the linux instrument work in prepare. The samples are dropped
until our start-time is set.

Doing it this way removes sysprof-cli and sysprofd greatly from the
overhead in the callgraph which is useful so that the user gets to see
what they really care about.

It has the added benefit that we're less likely to see the pkla processes
showing up from authorizing our D-Bus connection for creating per streams.
This commit is contained in:
Christian Hergert
2023-08-07 12:13:28 -07:00
parent ae93716c76
commit 4250abf81e
2 changed files with 25 additions and 46 deletions
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40
src/libsysprof/sysprof-linux-instrument.c
View File

@ -234,7 +234,11 @@ static DexFuture *
sysprof_linux_instrument_prepare_fiber (gpointer user_data)
{
SysprofRecording *recording = user_data;
g_autoptr(GDBusConnection) bus = NULL;
g_autoptr(GVariant) process_info_reply = NULL;
g_autoptr(GVariant) process_info = NULL;
g_autoptr(GError) error = NULL;
gint64 at_time;
g_assert (SYSPROF_IS_RECORDING (recording));
@ -247,34 +251,6 @@ sysprof_linux_instrument_prepare_fiber (gpointer user_data)
&error))
return dex_future_new_for_error (g_steal_pointer (&error));
return dex_future_new_for_boolean (TRUE);
}
static DexFuture *
sysprof_linux_instrument_prepare (SysprofInstrument *instrument,
SysprofRecording *recording)
{
g_assert (SYSPROF_IS_INSTRUMENT (instrument));
g_assert (SYSPROF_IS_RECORDING (recording));
return dex_scheduler_spawn (NULL, 0,
sysprof_linux_instrument_prepare_fiber,
g_object_ref (recording),
g_object_unref);
}
static DexFuture *
sysprof_linux_instrument_record_fiber (gpointer user_data)
{
SysprofRecording *recording = user_data;
g_autoptr(GDBusConnection) bus = NULL;
g_autoptr(GVariant) process_info_reply = NULL;
g_autoptr(GVariant) process_info = NULL;
g_autoptr(GError) error = NULL;
gint64 at_time;
g_assert (SYSPROF_IS_RECORDING (recording));
/* We need access to the bus to call various sysprofd API directly */
if (!(bus = dex_await_object (dex_bus_get (G_BUS_TYPE_SYSTEM), &error)))
return dex_future_new_for_error (g_steal_pointer (&error));
@ -303,15 +279,14 @@ sysprof_linux_instrument_record_fiber (gpointer user_data)
}
static DexFuture *
sysprof_linux_instrument_record (SysprofInstrument *instrument,
SysprofRecording *recording,
GCancellable *cancellable)
sysprof_linux_instrument_prepare (SysprofInstrument *instrument,
SysprofRecording *recording)
{
g_assert (SYSPROF_IS_INSTRUMENT (instrument));
g_assert (SYSPROF_IS_RECORDING (recording));
return dex_scheduler_spawn (NULL, 0,
sysprof_linux_instrument_record_fiber,
sysprof_linux_instrument_prepare_fiber,
g_object_ref (recording),
g_object_unref);
}
@ -341,7 +316,6 @@ sysprof_linux_instrument_class_init (SysprofLinuxInstrumentClass *klass)
instrument_class->list_required_policy = sysprof_linux_instrument_list_required_policy;
instrument_class->prepare = sysprof_linux_instrument_prepare;
instrument_class->record = sysprof_linux_instrument_record;
instrument_class->process_started = sysprof_linux_instrument_process_started;
}

31
src/libsysprof/sysprof-sampler.c
View File

@ -218,7 +218,8 @@ sysprof_sampler_perf_event_stream_cb (const SysprofPerfEvent *event,
break;
case PERF_RECORD_SAMPLE:
sysprof_sampler_add_callback (writer, cpu, &event->callchain);
if (recording->start_time != 0 && event->callchain.time >= recording->start_time)
sysprof_sampler_add_callback (writer, cpu, &event->callchain);
break;
case PERF_RECORD_THROTTLE:
@ -382,6 +383,22 @@ try_again:
g_ptr_array_add (prepare->sampler->perf_event_streams, g_steal_pointer (&stream));
}
/* Start all of the samplers immediately as we will drop events that
* are incoming before our start time. This allows the linux instrument
* to collect processes in prepare and not race to get new process info.
*/
for (guint i = 0; i < prepare->sampler->perf_event_streams->len; i++)
{
SysprofPerfEventStream *stream = g_ptr_array_index (prepare->sampler->perf_event_streams, i);
if (!sysprof_perf_event_stream_enable (stream, &error))
g_debug ("%s", error->message);
else
g_debug ("Sampler %d enabled", i);
g_clear_error (&error);
}
return dex_future_new_for_boolean (TRUE);
}
@ -432,18 +449,6 @@ sysprof_sampler_record_fiber (gpointer user_data)
g_assert (SYSPROF_IS_RECORDING (record->recording));
g_assert (DEX_IS_FUTURE (record->cancellable));
for (guint i = 0; i < record->sampler->perf_event_streams->len; i++)
{
SysprofPerfEventStream *stream = g_ptr_array_index (record->sampler->perf_event_streams, i);
if (!sysprof_perf_event_stream_enable (stream, &error))
g_debug ("%s", error->message);
else
g_debug ("Sampler %d enabled", i);
g_clear_error (&error);
}
if (!dex_await (dex_ref (record->cancellable), &error))
g_debug ("Sampler shutting down for reason: %s", error->message);