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-****************************************
- CDSChecker Readme
-****************************************
-
-Copyright (c) 2013 Regents of the University of California. All rights reserved.
-
-CDSChecker is distributed under the GPL v2.
-
-This README is divided into sections as follows:
-
- I. Overview
- II. Reading an execution trace
- A. References
-
-----------------------------------------
- I. Overview
-----------------------------------------
-
-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.
-
-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.
-
-Sample run instructions:
-
-$ make
-$ export LD_LIBRARY_PATH=.
-$ ./test/userprog.o # Runs simple test program
-$ ./test/userprog.o -h # Prints help information
-Copyright (c) 2013 Regents of the University of California. All rights reserved.
-Distributed under the GPLv2
-Written by Brian Norris and Brian Demsky
-
-Usage: ./test/userprog.o [MODEL-CHECKER OPTIONS] -- [PROGRAM ARGS]
-
-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:
--h, --help Display this help message and exit
--m, --liveness=NUM Maximum times a thread can read from the same write
- while other writes exist.
- Default: 0
--M, --maxfv=NUM Maximum number of future values that can be sent to
- the same read.
- Default: 0
--s, --maxfvdelay=NUM Maximum actions that the model checker will wait for
- a write from the future past the expected number
- of actions.
- Default: 6
--S, --fvslop=NUM Future value expiration sloppiness.
- Default: 4
--y, --yield Enable CHESS-like yield-based fairness support.
- Default: disabled
--Y, --yieldblock Prohibit an execution from running a yield.
- Default: disabled
--f, --fairness=WINDOW Specify a fairness window in which actions that are
- enabled sufficiently many times should receive
- priority for execution (not recommended).
- Default: 0
--e, --enabled=COUNT Enabled count.
- Default: 1
--b, --bound=MAX Upper length bound.
- Default: 0
--v, --verbose Print verbose execution information.
--u, --uninitialized=VALUE Return VALUE any load which may read from an
- uninitialized atomic.
- Default: 0
--t, --analysis=NAME Use Analysis Plugin.
--o, --options=NAME Option for previous analysis plugin.
- -o help for a list of options
- -- Program arguments follow.
-
-
-Note that we also provide a series of benchmarks (distributed separately),
-which can be placed under the benchmarks/ directory. After building CDSChecker,
-you can build and run the benchmarks as follows:
-
- cd benchmarks
- make
- ./run.sh barrier/barrier -y -m 2 # runs barrier test with fairness/memory liveness
- ./bench.sh # run all benchmarks twice, with timing results
-
-
-----------------------------------------
- II. 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. 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 and the reads-from relation).
-
-Columns:
-
- 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.
-
- 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.
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