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From: Robert Watson <rwatson@FreeBSD.org>
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Cc: performance@FreeBSD.org
Subject: Re: Fine-grained locking for POSIX local sockets (UNIX domain
	sockets)
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On Sat, 6 May 2006, Robert Watson wrote:

> Attached, please find a patch implementing more fine-grained locking for the 
> POSIX local socket subsystem (UNIX domain socket subsystem).  In the current 
> implementation, we use a single global subsystem lock to protect all local 
> IPC over the PF_LOCAL socket type.  This has low overhead, but can result in 
> significant contention, especially for workloads like MySQL which push a 
> great deal of data through UNIX domain sockets, and involve many parties. 
> The hope is that by improving granularity, we can reduce contention 
> sufficiently to overcome the added cost of increased locking overhead (a 
> side-effect of greater granularity).  At a high level, here are the changes 
> made:

FYI, you can download a copy unmangled by my and your mail systems at the 
following URL:

   http://www.watson.org/~robert/freebsd/netperf/20060506a-uds-fine-grain.diff

Robert N M Watson