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Big reader locks

Big reader locks

Posted Mar 19, 2010 16:53 UTC (Fri) by dvhart (subscriber, #19636)
Parent article: Big reader locks

What is it about this usage case that makes the brlock a more appropriate solution than RCU? They both cater to read-mostly datastructures, and both rely on some sort of global quiescent state (the brlock version being when the write acquires al NR_CPUS locks).


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Big reader locks

Posted Mar 23, 2010 18:47 UTC (Tue) by jzbiciak (subscriber, #5246) [Link]

I guess the major difference is that this one disallows any concurrency between readers and writers. In RCU, my understanding is that readers always get a "consistent" structure for as long as they need. A writer can start preparing a new copy while readers are still active.

In this, it sounds like a writer must wait until all readers are truly finished. When mounting/unmounting, that sounds like a useful, stronger semantic.

Or am I missing something?

Big reader locks

Posted Mar 25, 2010 15:36 UTC (Thu) by dvhart (subscriber, #19636) [Link]

Good point, I think you nailed it.


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