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About memory models and sequential consistency
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Horizon68
Jan 20, 2019, 1:18:51 PM1/20/19
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Hello...
About memory models and sequential consistency:
As you have noticed i am working with x86 architecture..
Even though x86 gives up on sequential consistency, it’s among the most
well-behaved architectures in terms of the crazy behaviors it allows.
Most other architectures implement even weaker memory models.
ARM memory model is notoriously underspecified, but is essentially a
form of weak ordering, which provides very few guarantees. Weak ordering
allows almost any operation to be reordered, which enables a variety of
hardware optimizations but is also a nightmare to program at the lowest
levels.
Read more here:
https://homes.cs.washington.edu/~bornholt/post/memory-models.html
Memory Models: x86 is TSO, TSO is Good
Essentially, the conclusion is that x86 in practice implements the old
SPARC TSO memory model.
The big take-away from the talk for me is that it confirms the
observation made may times before that SPARC TSO seems to be the optimal
memory model. It is sufficiently understandable that programmers can
write correct code without having barriers everywhere. It is
sufficiently weak that you can build fast hardware implementation that
can scale to big machines.
Read more here:
https://jakob.engbloms.se/archives/1435
Thank you,
Amine Moulay Ramdane.
About memory models and sequential consistency:
As you have noticed i am working with x86 architecture..
Even though x86 gives up on sequential consistency, it’s among the most
well-behaved architectures in terms of the crazy behaviors it allows.
Most other architectures implement even weaker memory models.
ARM memory model is notoriously underspecified, but is essentially a
form of weak ordering, which provides very few guarantees. Weak ordering
allows almost any operation to be reordered, which enables a variety of
hardware optimizations but is also a nightmare to program at the lowest
levels.
Read more here:
https://homes.cs.washington.edu/~bornholt/post/memory-models.html
Memory Models: x86 is TSO, TSO is Good
Essentially, the conclusion is that x86 in practice implements the old
SPARC TSO memory model.
The big take-away from the talk for me is that it confirms the
observation made may times before that SPARC TSO seems to be the optimal
memory model. It is sufficiently understandable that programmers can
write correct code without having barriers everywhere. It is
sufficiently weak that you can build fast hardware implementation that
can scale to big machines.
Read more here:
https://jakob.engbloms.se/archives/1435
Thank you,
Amine Moulay Ramdane.
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