Class used to decode a multi-cpu Intel PT trace. More...

#include <TraceIntelPTMultiCpuDecoder.h>

Public Member Functions
	TraceIntelPTMultiCpuDecoder (TraceIntelPTSP trace_sp)

llvm::Expected< DecodedThreadSP >	Decode (Thread &thread)

bool	TracesThread (lldb::tid_t tid) const

size_t	GetNumContinuousExecutionsForThread (lldb::tid_t tid) const

size_t	GePSBBlocksCountForThread (lldb::tid_t tid) const

size_t	GetTotalContinuousExecutionsCount () const

size_t	GetUnattributedPSBBlocksCount () const

size_t	GetTotalPSBBlocksCount () const

llvm::Expected< std::optional< uint64_t > >	FindLowestTSC ()

Private Member Functions
llvm::Error	CorrelateContextSwitchesAndIntelPtTraces ()
	Traverse the context switch traces and the basic intel pt continuous subtraces and produce a list of continuous executions for each process and thread.

llvm::Expected< llvm::DenseMap< lldb::tid_t, std::vector< IntelPTThreadContinousExecution > > >	DoCorrelateContextSwitchesAndIntelPtTraces ()
	Produce a mapping from thread ids to the list of continuos executions with their associated intel pt subtraces.

TraceIntelPTSP	GetTrace ()

Private Attributes
std::weak_ptr< TraceIntelPT >	m_trace_wp

std::set< lldb::tid_t >	m_tids

std::optional< llvm::DenseMap< lldb::tid_t, std::vector< IntelPTThreadContinousExecution > > >	m_continuous_executions_per_thread

llvm::DenseMap< lldb::tid_t, DecodedThreadSP >	m_decoded_threads

std::optional< std::string >	m_setup_error
	This variable will not be std::nullopt if a severe error happened during the setup of the decoder and we don't want decoding to be reattempted.

uint64_t	m_unattributed_psb_blocks = 0

uint64_t	m_total_psb_blocks = 0

Detailed Description

Class used to decode a multi-cpu Intel PT trace.

It assumes that each thread could have potentially been executed on different cpu cores. It uses a context switch trace per CPU with timestamps to identify which thread owns each Intel PT decoded instruction and in which order. It also assumes that the Intel PT data and context switches might have gaps in their traces due to contention or race conditions. Finally, it assumes that a tid is not repeated twice for two different threads because of the shortness of the intel pt trace.

This object should be recreated after every stop in the case of live processes.

Definition at line 32 of file TraceIntelPTMultiCpuDecoder.h.

Constructor & Destructor Documentation

◆ TraceIntelPTMultiCpuDecoder()

TraceIntelPTMultiCpuDecoder::TraceIntelPTMultiCpuDecoder ( TraceIntelPTSP trace_sp )

Parameters

[in] TraceIntelPT The trace object to be decoded

Definition at line 19 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_tids.

Member Function Documentation

◆ CorrelateContextSwitchesAndIntelPtTraces()

Error TraceIntelPTMultiCpuDecoder::CorrelateContextSwitchesAndIntelPtTraces ( )

private

Traverse the context switch traces and the basic intel pt continuous subtraces and produce a list of continuous executions for each process and thread.

See DoCorrelateContextSwitchesAndIntelPtTraces.

Any errors are stored in m_setup_error.

Definition at line 177 of file TraceIntelPTMultiCpuDecoder.cpp.

References DoCorrelateContextSwitchesAndIntelPtTraces(), GetTrace(), m_continuous_executions_per_thread, m_setup_error, and lldb_private::toString().

Referenced by Decode().

◆ Decode()

Expected< DecodedThreadSP > TraceIntelPTMultiCpuDecoder::Decode ( Thread & thread )

Returns: A DecodedThread for the thread by decoding its instructions on all CPUs, sorted by TSCs. An llvm::Error is returned if the decoder couldn't be properly set up.

Definition at line 59 of file TraceIntelPTMultiCpuDecoder.cpp.

References CorrelateContextSwitchesAndIntelPtTraces(), lldb_private::UserID::GetID(), GetTrace(), lldb_private::IntelPTDataKinds::kIptTrace, and m_decoded_threads.

◆ DoCorrelateContextSwitchesAndIntelPtTraces()

Expected< DenseMap< lldb::tid_t, std::vector< IntelPTThreadContinousExecution > > > TraceIntelPTMultiCpuDecoder::DoCorrelateContextSwitchesAndIntelPtTraces ( )

private

Produce a mapping from thread ids to the list of continuos executions with their associated intel pt subtraces.

Definition at line 113 of file TraceIntelPTMultiCpuDecoder.cpp.

References lldb_private::trace_intel_pt::DecodePerfContextSwitchTrace(), GetPSBBlocksForCPU(), GetTrace(), lldb_private::IntelPTDataKinds::kPerfContextSwitchTrace, m_total_psb_blocks, m_unattributed_psb_blocks, and lldb_private::trace_intel_pt::IntelPTThreadContinousExecution::psb_blocks.

Referenced by CorrelateContextSwitchesAndIntelPtTraces().

◆ FindLowestTSC()

Expected< std::optional< uint64_t > > TraceIntelPTMultiCpuDecoder::FindLowestTSC ( )

Returns: The lowest TSC value in this trace if available, std::nullopt if the trace is empty or the trace contains no timing information, or an llvm::Error if it was not possible to set up the decoder.

Definition at line 37 of file TraceIntelPTMultiCpuDecoder.cpp.

References lldb_private::trace_intel_pt::FindLowestTSCInTrace(), GetTrace(), and lldb_private::IntelPTDataKinds::kIptTrace.

◆ GePSBBlocksCountForThread()

size_t TraceIntelPTMultiCpuDecoder::GePSBBlocksCountForThread ( lldb::tid_t tid ) const

Returns: The number of PSB blocks for a given thread in all cores.

Definition at line 220 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_continuous_executions_per_thread, and lldb_private::trace_intel_pt::IntelPTThreadContinousExecution::psb_blocks.

◆ GetNumContinuousExecutionsForThread()

size_t TraceIntelPTMultiCpuDecoder::GetNumContinuousExecutionsForThread ( lldb::tid_t tid ) const

Returns: The number of continuous executions found for the given tid.

Definition at line 200 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_continuous_executions_per_thread.

◆ GetTotalContinuousExecutionsCount()

size_t TraceIntelPTMultiCpuDecoder::GetTotalContinuousExecutionsCount ( ) const

Returns: The total number of continuous executions found across CPUs.

Definition at line 210 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_continuous_executions_per_thread.

◆ GetTotalPSBBlocksCount()

size_t TraceIntelPTMultiCpuDecoder::GetTotalPSBBlocksCount ( ) const

Returns: The total number of PSB blocks in all cores.

Definition at line 236 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_total_psb_blocks.

◆ GetTrace()

TraceIntelPTSP TraceIntelPTMultiCpuDecoder::GetTrace ( )

private

Definition at line 29 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_trace_wp.

Referenced by CorrelateContextSwitchesAndIntelPtTraces(), Decode(), DoCorrelateContextSwitchesAndIntelPtTraces(), and FindLowestTSC().

◆ GetUnattributedPSBBlocksCount()

size_t TraceIntelPTMultiCpuDecoder::GetUnattributedPSBBlocksCount ( ) const

Returns: The number of psb blocks in all cores that couldn't be matched with a thread execution coming from context switch traces.

Definition at line 232 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_unattributed_psb_blocks.

◆ TracesThread()

bool TraceIntelPTMultiCpuDecoder::TracesThread ( lldb::tid_t tid ) const

Returns: true if the given tid is managed by this decoder, regardless of whether there's tracing data associated to it or not.

Definition at line 33 of file TraceIntelPTMultiCpuDecoder.cpp.

References m_tids.

Member Data Documentation

◆ m_continuous_executions_per_thread

std::optional< llvm::DenseMap<lldb::tid_t, std::vector<IntelPTThreadContinousExecution> > > lldb_private::trace_intel_pt::TraceIntelPTMultiCpuDecoder::m_continuous_executions_per_thread

private

Definition at line 98 of file TraceIntelPTMultiCpuDecoder.h.

Referenced by CorrelateContextSwitchesAndIntelPtTraces(), GePSBBlocksCountForThread(), GetNumContinuousExecutionsForThread(), and GetTotalContinuousExecutionsCount().