Date: Tue, 25 May 2004 01:54:10 -0500 From: Alan Cox <alc@cs.rice.edu> To: dillon@backplane.com, arch@freebsd.org Subject: Re: Network Stack Locking Message-ID: <20040525065410.GA23877@cs.rice.edu>
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>:Sounds a lot like a lot of the Mach IPC optimizations, including their use >:of continuations during IPC to avoid a full context switch. >: >:Robert N M Watson FreeBSD Core Team, TrustedBSD Projects >:robert@fledge.watson.org Senior Research Scientist, McAfee Research > > Well, I like the performance aspects of a continuation mechanism, but > I really dislike the memory overhead. Even a minimal stack is > expensive when you multiply it by potentially hundreds of thousands > of 'blocking' entities such as PCBs.. say, a TCP output stream. > Because of this the overhead and cache pollution generated by the > continuation mechanism increases as system load increases rather > then decreases. When the explicit continuation mechanism was used, the thread's stack was freed when the thread blocked and a new stack allocated when the thread was restarted. Here is a URL: http://citeseer.ist.psu.edu/draves91using.html. Notice the mention of space reduction in the abstract. It's worth reading. Alan
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