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Re: Dynamically allocated locks

On Mar 23, 2008, at 10:52 AM, Andrew Doran wrote:


This patch allows for dynamically allocated locks.

Each lock gets its own cache line, which can reduce cache coherency costs when the lock is very active. The locks are reference counted so can be shared between objects. That could be used for the two ends of a Unix socket
connection, or to share a lock between clone()d processes in order to
protect common state like signal actions, etc.

Any objections?

Yes. One / cacheline size is a dramatic waste of space. Some systems have 128 bytes per cacheline. On systems with small caches or UP systems it's
extremely expensive.

Other than that its fine.  I can see not crossing a cacheline boundary,
but only 1 / cacheline is just wrong.

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