On Tue, 2018-02-27 at 16:40 +0000, Simon Wright wrote: > On 27 Feb 2018, at 12:56, Ruslan Nikolaev via gcc <gcc@gcc.gnu.org> wrote: > > > > And all this mess to accommodate almost non-existent case when someone > > wants to use atomic_load on read-only memory for wide types, in which no > > good solution exists anyway > > Sorry to butt in, but - if it's ROM why would you need atomic load anyway? > (of course, if it's just a constant view of the object, reason is obvious)
Consider a producer-consumer relationship between two processes where the producer doesn't want to wait for the consumer. For example, the producer could be an application that's being traced, and the consumer is a trace aggregation tool. The producer can provide a read-only mapping to the consumer, and put a nonblocking ring buffer or something similar in there. That allows the consumer to read, but it still needs atomic access because the consumer is modifying the ring buffer concurrently.
