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Read-copy-update (RCU) operations with reduced memory barrier usage

  • US 7,353,346 B2
  • Filed: 03/24/2006
  • Issued: 04/01/2008
  • Est. Priority Date: 03/24/2006
  • Status: Active Grant
First Claim
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1. A method comprising:

  • to update contents of a section of memory,copying a global flip-counter bit to a local flip-counter bit, the global flip-counter bit specifying which of a first set of per-processor counters and a second set of per-processor counters is a current set of per-processor counters and which is a last set of per-processor counters, the global flip-counter bit also specifying which of a first set of per-processor need-memory-barrier bits and a second set of per-processor need-memory-barrier bits is a current set of per-processor need-memory-barrier bits and which is a last set of per-processor need-memory-barrier bits;

    where attempting to acquire a flip-counter-bit lock on the global-flip-counter bit is successful,where the global flip-counter bit has not changed while acquiring the flip-counter-bit lock,where all of the last set of per-processor counters are zero, such that none of a plurality of threads being executed by a plurality of processors corresponding to the last set of per-processor counters are currently executing a critical read operation on the section of memory,where all of the last set of per-processor need-memory-barrier bits are zero, such that none of the processors needs to execute a memory barrier,setting each of the current set of per-processor need-memory-barrier bits to one, using the local flip-counter bit;

    inverting the global flip-counter bit; and

    ,releasing the flip-counter-bit lock.

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