Hello! The topic of memory-ordering recipes came up at the Linux Plumbers Conference microconference on Friday, so I thought that I should summarize what is currently "out there":
1. memory-barriers.txt: A bit rambling and diffuse for a recipes document. 2. https://www.kernel.org/pub/linux/kernel/people/paulmck/LWNLinuxMM/Examples.html Many of the examples are on-point, but this is aimed more at understanding the memory model than at an organized set of recipes. 3. https://www.kernel.org/pub/linux/kernel/people/paulmck/LWNLinuxMM/Examples.html Slides 15-20. Again, some of the litmus tests are on-point, but the focus is more on understanding the memory model than on an organized set of recipes. So what litmus tests are needed? Here is my initial set: 1. Release-acquire chains, AKA ISA2, Z6.2, LB, and 3.LB Lots of variety here, can in some cases substitute: a. READ_ONCE() for smp_load_acquire() b. WRITE_ONCE() for smp_store_release() c. Dependencies for both smp_load_acquire() and smp_store_release(). d. smp_wmb() for smp_store_release() in first thread of ISA2 and Z6.2. e. smp_rmb() for smp_load_acquire() in last thread of ISA2. 2. MP (see test6.pdf for nickname translation) a. smp_store_release() / smp_load_acquire() b. rcu_assign_pointer() / rcu_dereference() c. smp_wmb() / smp_rmb() d. Replacing either of the above with smp_mb() 3. SB a. smp_mb(), as in lockless wait-wakeup coordination. And as in sys_membarrier()-scheduler coordination, for that matter. Others? Thanx, Paul