What is RCU and how does it differ from reader-writer locks?
RCU (Read-Copy-Update) eliminates read-side blocking entirely. Instead of holding a lock while readers execute, a writer makes a copy, mutates the copy off-to-the-side, atomically flips a single pointer, then waits for a grace period before freeing the old version. Readers never block and scale linearly with CPU count.
Answered in
How Linux RCU Unlocks Read-Side ScalingRCU lets millions of readers run lock-free while a single writer updates state by copying, mutating off-to-the-side, and atomically flipping a pointer.
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