On 2018-Jul-06 09:47:00 -0600, Warner Losh <i...@bsdimp.com> wrote: >On UP systems, these additional opcodes are harmless. They take a few extra >cycles (since they lock an uncontested bus) and add a couple extra memory >barriers (which will be NOPs). On MP systems, atomics now work by default.
Atomics in modules used to work by default (at least on x86) - they were explicitly not inlined so that modules on UP systems didn't have to include the lock and barrier instructions that were very expensive on some systems 20 years ago. That said, those systems are (hopefully) all dead now so moving to inlining SMP versions of atomic operations in modules is probably the correct decision now. -- Peter Jeremy
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