On Mon, Mar 02, 2020 at 12:56:59PM -0500, Alan Stern wrote: > 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! Applied, thank you both! Thanx, Paul
