Re: Updated fine-grain locking patch for UNIX domain sockets


On Mon, 3 Jul 2006, Robert Watson wrote:

On Mon, 3 Jul 2006, David Xu wrote:

I found 5% performance decrease on dual P4, maybe P4 is quite bad when doing atomic operation. ;-) Thanks,

When I've measured, generally, yes, P4 performance has been abysmal for synchronization operations, both atomic operations and CPU-local interrupt disabling, etc.

I suspect rwlocks could use a bit of optimization in the contention case. I've not dug into the code, so I'm not clear how they compare with respect to adaptive behavior.

I ran some micro-benchmarks, and rwlocks don't perform substantially differently from sleep mutexes for uncontended operation -- I've not measured cost under contention, however.

Robert N M Watson
Computer Laboratory
University of Cambridge
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