****************************************
-CDSChecker Readme
+ CDSChecker Readme
****************************************
Copyright (c) 2013 Regents of the University of California. All rights reserved.
CDSChecker is distributed under the GPL v2.
-CDSChecker compiles as a dynamically-linked shared library by simply running
-'make'. It should compile on Linux and Mac OSX, and has been tested with LLVM
-(clang/clang++) and GCC.
+This README is divided into sections as follows:
-Test programs should use the standard C11/C++11 library headers
-(<atomic>/<stdatomic.h>, <mutex>, <condition_variable>, <thread.h>) and must
-name their main routine as user_main(int, char**) rather than main(int, char**).
-We only support C11 thread syntax (thrd_t, etc. from <thread.h>).
+ I. Overview
+ II. Basic build and run
+ III. Running your own code
+ IV. Reading an execution trace
+Appendix
+ A. References
-Test programs may also use our included happens-before race detector by
-including <librace.h> and utilizing the appropriate functions
-(store_{8,16,32,64}() and load_{8,16,32,64}()) for loading/storing data from/to
-from non-atomic shared memory.
+----------------------------------------
+ I. Overview
+----------------------------------------
-Test programs should be compiled against our shared library (libmodel.so) using
-the headers in the include/ directory. Then the shared library must be made
-available to the dynamic linker, using the LD_LIBRARY_PATH environment
-variable, for instance.
+CDSChecker is a model checker for C11/C++11 exhaustively explores the behaviors
+of code under the C11/C++11 memory model. It uses partial order reduction to
+eliminate redundant executions to significantly shrink the state space.
+The model checking algorithm is described in more detail in this paper
+(currently under review):
+
+ http://demsky.eecs.uci.edu/publications/c11modelcheck.pdf
+
+It is designed to support unit tests on concurrent data structure written using
+C11/C++11 atomics.
+
+CDSChecker is constructed as a dynamically-linked shared library which
+implements the C and C++ atomic types and portions of the other thread-support
+libraries of C/C++ (e.g., std::atomic, std::mutex, etc.). Notably, we only
+support the C version of threads (i.e., thrd_t and similar, from <threads.h>),
+because C++ threads require features which are only available to a C++11
+compiler (and we want to support others, at least for now).
+
+CDSChecker should compile on Linux and Mac OSX with no dependencies and has been
+tested with LLVM (clang/clang++) and GCC. It likely can be ported to other *NIX
+flavors. We have not attempted to port to Windows.
+
+Other references can be found at the main project page:
+
+ http://demsky.eecs.uci.edu/c11modelchecker.php
+
+----------------------------------------
+ II. Basic build and run
+----------------------------------------
Sample run instructions:
Usage: ./test/userprog.o [MODEL-CHECKER OPTIONS] -- [PROGRAM ARGS]
-MODLE-CHECKER OPTIONS can be any of the model-checker options listed below. Arguments
+MODEL-CHECKER OPTIONS can be any of the model-checker options listed below. Arguments
provided after the `--' (the PROGRAM ARGS) are passed to the user program.
Model-checker options:
-u, --uninitialized=VALUE Return VALUE any load which may read from an
uninitialized atomic.
Default: 0
--c, --analysis Use SC Trace Analysis.
+-t, --analysis=NAME Use Analysis Plugin.
+-o, --options=NAME Option for previous analysis plugin.
+ -o help for a list of options
-- Program arguments follow.
make
./run.sh barrier/barrier -y -m 2 # runs barrier test with fairness/memory liveness
./bench.sh # run all benchmarks twice, with timing results
+
+----------------------------------------
+ III. Running your own code
+----------------------------------------
+
+We provide several test and sample programs under the test/ directory, which
+should compile and run with no trouble. Of course, you likely want to test your
+own code. To do so, you need to perform a few steps.
+
+First, because CDSChecker executes your program dozens (if not hundreds or
+thousands) of times, you will have the most success if your code is written as a
+unit test and not as a full-blown program.
+
+Next, test programs should use the standard C11/C++11 library headers
+(<atomic>/<stdatomic.h>, <mutex>, <condition_variable>, <thread.h>) and must
+name their main routine as user_main(int, char**) rather than main(int, char**).
+We only support C11 thread syntax (thrd_t, etc. from <thread.h>).
+
+Test programs may also use our included happens-before race detector by
+including <librace.h> and utilizing the appropriate functions
+(store_{8,16,32,64}() and load_{8,16,32,64}()) for loading/storing data from/to
+from non-atomic shared memory.
+
+Test programs should be compiled against our shared library (libmodel.so) using
+the headers in the include/ directory. Then the shared library must be made
+available to the dynamic linker, using the LD_LIBRARY_PATH environment
+variable, for instance.
+
+----------------------------------------
+ IV. Reading an execution trace
+----------------------------------------
+
+When CDSChecker detects a bug in your program (or when run with the --verbose
+flag), it prints the output of the program run (STDOUT) along with some summary
+trace information for the execution in question. The trace is given as a
+sequence of lines, where each line represents an operation in the execution
+trace. These lines are ordered by the order in which they were run by CDSChecker
+(i.e., the "execution order"), which does not necessarily align with the "order"
+of the values observed (i.e., the modification order or the reads-from
+relation).
+
+The following list describes each of the columns in the execution trace output:
+
+ o #: The sequence number within the execution. That is, sequence number "9"
+ means the operation was the 9th operation executed by CDSChecker. Note that
+ this represents the execution order, not necessarily any other order (e.g.,
+ modification order or reads-from).
+
+ o t: The thread number
+
+ o Action type: The type of operation performed
+
+ o MO: The memory-order for this operation (i.e., memory_order_XXX, where XXX is
+ relaxed, release, acquire, rel_acq, or seq_cst)
+
+ o Location: The memory location on which this operation is operating. This is
+ well-defined for atomic write/read/RMW, but other operations are subject to
+ CDSChecker implementation details.
+
+ o Value: For reads/writes/RMW, the value returned by the operation. Note that
+ for RMW, this is the value that is *read*, not the value that was *written*.
+ For other operations, 'value' may have some CDSChecker-internal meaning, or
+ it may simply be a don't-care (such as 0xdeadbeef).
+
+ o Rf: For reads, the sequence number of the operation from which it reads.
+ [Note: If the execution is a partial, infeasible trace (labeled INFEASIBLE),
+ as printed during --verbose execution, reads may not be resolved and so may
+ have Rf=? or Rf=Px, where x is a promised future value.]
+
+ o CV: The clock vector, encapsulating the happens-before relation (see our
+ paper, or the C/C++ memory model itself). We use a Lamport-style clock vector
+ similar to [1]. The "clock" is just the sequence number (#). The clock vector
+ can be read as follows:
+
+ Each entry is indexed as CV[i], where
+
+ i = 0, 1, 2, ..., <number of threads>
+
+ So for any thread i, we say CV[i] is the sequence number of the most recent
+ operation in thread i such that operation i happens-before this operation.
+ Notably, thread 0 is reserved as a dummy thread for certain CDSChecker
+ operations.
+
+See the following example trace:
+
+------------------------------------------------------------------------------------
+# t Action type MO Location Value Rf CV
+------------------------------------------------------------------------------------
+1 1 thread start seq_cst 0x7f68ff11e7c0 0xdeadbeef ( 0, 1)
+2 1 init atomic relaxed 0x601068 0 ( 0, 2)
+3 1 init atomic relaxed 0x60106c 0 ( 0, 3)
+4 1 thread create seq_cst 0x7f68fe51c710 0x7f68fe51c6e0 ( 0, 4)
+5 2 thread start seq_cst 0x7f68ff11ebc0 0xdeadbeef ( 0, 4, 5)
+6 2 atomic read relaxed 0x60106c 0 3 ( 0, 4, 6)
+7 1 thread create seq_cst 0x7f68fe51c720 0x7f68fe51c6e0 ( 0, 7)
+8 3 thread start seq_cst 0x7f68ff11efc0 0xdeadbeef ( 0, 7, 0, 8)
+9 2 atomic write relaxed 0x601068 0 ( 0, 4, 9)
+10 3 atomic read relaxed 0x601068 0 2 ( 0, 7, 0, 10)
+11 2 thread finish seq_cst 0x7f68ff11ebc0 0xdeadbeef ( 0, 4, 11)
+12 3 atomic write relaxed 0x60106c 0x2a ( 0, 7, 0, 12)
+13 1 thread join seq_cst 0x7f68ff11ebc0 0x2 ( 0, 13, 11)
+14 3 thread finish seq_cst 0x7f68ff11efc0 0xdeadbeef ( 0, 7, 0, 14)
+15 1 thread join seq_cst 0x7f68ff11efc0 0x3 ( 0, 15, 11, 14)
+16 1 thread finish seq_cst 0x7f68ff11e7c0 0xdeadbeef ( 0, 16, 11, 14)
+HASH 4073708854
+------------------------------------------------------------------------------------
+
+Now consider, for example, operation 10:
+
+This is the 10th operation in the execution order. It is an atomic read-relaxed
+operation performed by thread 3 at memory address 0x601068. It reads the value
+"0", which was written by the 2nd operation in the execution order. Its clock
+vector consists of the following values:
+
+ CV[0] = 0, CV[1] = 7, CV[2] = 0, CV[3] = 10
+
+
+----------------------------------------
+ A. References
+----------------------------------------
+
+[1] L. Lamport. Time, clocks, and the ordering of events in a distributed
+ system. CACM, 21(7):558–565, July 1978.
projects / cdsspec-compiler.git / blobdiff