On Mon, 2 Mar 2020, Marco Elver wrote: > The definition of "conflict" should not include the type of access nor > whether the accesses are concurrent or not, which this patch addresses. > The definition of "data race" remains unchanged. > > The definition of "conflict" as we know it and is cited by various > papers on memory consistency models appeared in [1]: "Two accesses to > the same variable conflict if at least one is a write; two operations > conflict if they execute conflicting accesses." > > The LKMM as well as the C11 memory model are adaptations of > data-race-free, which are based on the work in [2]. Necessarily, we need > both conflicting data operations (plain) and synchronization operations > (marked). For example, C11's definition is based on [3], which defines a > "data race" as: "Two memory operations conflict if they access the same > memory location, and at least one of them is a store, atomic store, or > atomic read-modify-write operation. In a sequentially consistent > execution, two memory operations from different threads form a type 1 > data race if they conflict, at least one of them is a data operation, > and they are adjacent in <T (i.e., they may be executed concurrently)." > > [1] D. Shasha, M. Snir, "Efficient and Correct Execution of Parallel > Programs that Share Memory", 1988. > URL: http://snir.cs.illinois.edu/listed/J21.pdf > > [2] S. Adve, "Designing Memory Consistency Models for Shared-Memory > Multiprocessors", 1993. > URL: http://sadve.cs.illinois.edu/Publications/thesis.pdf > > [3] H.-J. Boehm, S. Adve, "Foundations of the C++ Concurrency Memory > Model", 2008. > URL: https://www.hpl.hp.com/techreports/2008/HPL-2008-56.pdf > > Signed-off-by: Marco Elver <elver@xxxxxxxxxx> > Co-developed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> > --- > v3: > * Apply Alan's suggestion. > * s/two race candidates/race candidates/ Looks good! Alan
