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Cc: freebsd-performance@freebsd.org
Subject: Re: Updated fine-grain locking patch for UNIX domain sockets
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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.

Robert N M Watson
Computer Laboratory
University of Cambridge