Date: Mon, 24 May 2004 23:49:11 -0400 (EDT) From: Robert Watson <rwatson@FreeBSD.org> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: Eivind Eklund <eivind@FreeBSD.org> Subject: Re: Network Stack Locking Message-ID: <Pine.NEB.3.96L.1040524234219.98946L-100000@fledge.watson.org> In-Reply-To: <200405250339.i4P3dLBX090505@apollo.backplane.com>
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On Mon, 24 May 2004, Matthew Dillon wrote: > Deep message queues aren't necessarily a problem and, in fact, having > one or two dozen messages backed up in a protocol thread's message > port is actually good because the thread can then process all the > messages in a tight loop (cpu and cache locality of reference). If > designed properly, this directly mitigates the cost of a thread switch > as system load increases. So message queueing has the opposite effect... > per-unit handling overhead *decreases* as system load increases. Actually, this was the specific point I was making also :-). The question I was asking was about the depth of the message queues between protocol stack layers in actual measurements -- are you observing substantial coallescing between layers as a result of the queues at this point? I'm looking for emperical evidence that the coallescing does make up for the extra context switches of the model in practice... Robert N M Watson FreeBSD Core Team, TrustedBSD Projects robert@fledge.watson.org Senior Research Scientist, McAfee Research
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