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wall time, user time, and system time since a process started. For walltime, we currently use TimeValue's interface and a global initializer to compute a close approximation of total process runtime. For user time, this adds support for an somewhat more precise timing mechanism -- clock_gettime with the CLOCK_PROCESS_CPUTIME_ID clock selected. For system time, we have to do a full getrusage call to extract the system time from the OS. This is expensive but unavoidable. In passing, clean up the implementation of the old APIs and fix some latent bugs in the Windows code. This might have manifested on Windows ARM systems or other systems with strange 64-bit integer behavior. The old API for this both user time and system time simultaneously from a single getrusage call. While this results in fewer system calls, it also results in a lower precision user time and if only user time is desired, it introduces a higher overhead. It may be worthwhile to switch some of the pass timers to not track system time and directly track user and wall time. The old API also tracked walltime in a confusing way -- it just set it to the current walltime rather than providing any measure of wall time since the process started the way buth user and system time are tracked. The new API is more consistent here. The plan is to eventually implement these methods for a *child* process by using the wait3(2) system call to populate an rusage struct representing the whole subprocess execution. That way, after waiting on a child process its stats will become accurate and cheap to query. llvm-svn: 171551 |
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| .. | ||
| Unix | ||
| Windows | ||
| Allocator.cpp | ||
| APFloat.cpp | ||
| APInt.cpp | ||
| APSInt.cpp | ||
| Atomic.cpp | ||
| BlockFrequency.cpp | ||
| BranchProbability.cpp | ||
| circular_raw_ostream.cpp | ||
| CMakeLists.txt | ||
| CommandLine.cpp | ||
| ConstantRange.cpp | ||
| COPYRIGHT.regex | ||
| CrashRecoveryContext.cpp | ||
| DAGDeltaAlgorithm.cpp | ||
| DataExtractor.cpp | ||
| DataStream.cpp | ||
| Debug.cpp | ||
| DeltaAlgorithm.cpp | ||
| Disassembler.cpp | ||
| Dwarf.cpp | ||
| DynamicLibrary.cpp | ||
| Errno.cpp | ||
| ErrorHandling.cpp | ||
| FileOutputBuffer.cpp | ||
| FileUtilities.cpp | ||
| FoldingSet.cpp | ||
| FormattedStream.cpp | ||
| GraphWriter.cpp | ||
| Hashing.cpp | ||
| Host.cpp | ||
| IncludeFile.cpp | ||
| IntEqClasses.cpp | ||
| IntervalMap.cpp | ||
| IntrusiveRefCntPtr.cpp | ||
| IsInf.cpp | ||
| IsNAN.cpp | ||
| LLVMBuild.txt | ||
| Locale.cpp | ||
| LocaleGeneric.inc | ||
| LocaleWindows.inc | ||
| LocaleXlocale.inc | ||
| LockFileManager.cpp | ||
| Makefile | ||
| ManagedStatic.cpp | ||
| Memory.cpp | ||
| MemoryBuffer.cpp | ||
| MemoryObject.cpp | ||
| Mutex.cpp | ||
| Path.cpp | ||
| PathV2.cpp | ||
| PluginLoader.cpp | ||
| PrettyStackTrace.cpp | ||
| Process.cpp | ||
| Program.cpp | ||
| raw_os_ostream.cpp | ||
| raw_ostream.cpp | ||
| README.txt.system | ||
| regcclass.h | ||
| regcname.h | ||
| regcomp.c | ||
| regengine.inc | ||
| regerror.c | ||
| regex2.h | ||
| regex_impl.h | ||
| Regex.cpp | ||
| regexec.c | ||
| regfree.c | ||
| regstrlcpy.c | ||
| regutils.h | ||
| RWMutex.cpp | ||
| SearchForAddressOfSpecialSymbol.cpp | ||
| Signals.cpp | ||
| SmallPtrSet.cpp | ||
| SmallVector.cpp | ||
| SourceMgr.cpp | ||
| Statistic.cpp | ||
| StreamableMemoryObject.cpp | ||
| StringExtras.cpp | ||
| StringMap.cpp | ||
| StringPool.cpp | ||
| StringRef.cpp | ||
| system_error.cpp | ||
| SystemUtils.cpp | ||
| TargetRegistry.cpp | ||
| Threading.cpp | ||
| ThreadLocal.cpp | ||
| Timer.cpp | ||
| TimeValue.cpp | ||
| ToolOutputFile.cpp | ||
| Triple.cpp | ||
| Twine.cpp | ||
| Valgrind.cpp | ||
| YAMLParser.cpp | ||
| YAMLTraits.cpp | ||
Design Of lib/System
====================
The software in this directory is designed to completely shield LLVM from any
and all operating system specific functionality. It is not intended to be a
complete operating system wrapper (such as ACE), but only to provide the
functionality necessary to support LLVM.
The software located here, of necessity, has very specific and stringent design
rules. Violation of these rules means that cracks in the shield could form and
the primary goal of the library is defeated. By consistently using this library,
LLVM becomes more easily ported to new platforms since the only thing requiring
porting is this library.
Complete documentation for the library can be found in the file:
llvm/docs/SystemLibrary.html
or at this URL:
http://llvm.org/docs/SystemLibrary.html
While we recommend that you read the more detailed documentation, for the
impatient, here's a high level summary of the library's requirements.
1. No system header files are to be exposed through the interface.
2. Std C++ and Std C header files are okay to be exposed through the interface.
3. No exposed system-specific functions.
4. No exposed system-specific data.
5. Data in lib/System classes must use only simple C++ intrinsic types.
6. Errors are handled by returning "true" and setting an optional std::string
7. Library must not throw any exceptions, period.
8. Interface functions must not have throw() specifications.
9. No duplicate function impementations are permitted within an operating
system class.
To accomplish these requirements, the library has numerous design criteria that
must be satisfied. Here's a high level summary of the library's design criteria:
1. No unused functionality (only what LLVM needs)
2. High-Level Interfaces
3. Use Opaque Classes
4. Common Implementations
5. Multiple Implementations
6. Minimize Memory Allocation
7. No Virtual Methods