memory一致性模型
https://homes.cs.washington.edu/~bornholt/post/memory-models.html
https://www.cs.cmu.edu/afs/cs/academic/class/15418-s12/www/lectures/14_relaxedReview.pdf
https://content.riscv.org/wp-content/uploads/2018/05/14.25-15.00-RISCVMemoryModelTutorial.pdf
https://inst.eecs.berkeley.edu/~cs152/sp18/lectures/L19-MCM.pptx
