Messages in this thread |  | | Date | Mon, 08 Oct 2001 19:18:47 -0700 (PDT) | Subject | Re: RFC: patch to allow lock-free traversal of lists with insertion | From | "David S. Miller" <> |
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From: "Paul E. McKenney" <pmckenne@us.ibm.com> Date: Mon, 8 Oct 2001 18:55:24 -0700 (PDT)
I am particularly interested in comments from people who understand the detailed operation of the SPARC membar instruction and the PARISC SYNC instruction. My belief is that the membar("#SYNC") and SYNC instructions are sufficient,
SYNC is sufficient but way too strict. You don't explicitly say what you need to happen. If you need all previous stores to finish before all subsequent memory operations then:
membar #StoreStore | #StoreLoad
is sufficient. If you need all previous memory operations to finish before all subsequent stores then:
membar #StoreStore | #LoadStore
is what you want.
Thoughts?
I think if you need to perform IPIs and junk like that to make the memory barrier happen correctly, just throw your code away and use a spinlock instead.
Franks a lot, David S. Miller davem@redhat.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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