Date: Wed, 10 Jan 2007 14:22:56 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: Craig Rodrigues <rodrigc@crodrigues.org>, Randall Stewart <rrs@cisco.com>, freebsd-current@freebsd.org Subject: Re: Witness warning with SCTP Message-ID: <20070110142100.G52843@fledge.watson.org> In-Reply-To: <200701091426.36740.jhb@freebsd.org> References: <20070107171034.GA13836@crodrigues.org> <45A139CF.3090909@cisco.com> <20070107185228.W41371@fledge.watson.org> <200701091426.36740.jhb@freebsd.org>
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On Tue, 9 Jan 2007, John Baldwin wrote: > Either that or use an sx lock to close the pcb alloc race instead and don't > hold mutexes while calling hashinit(). I think this is a good point -- I've generally been restructuring PCB init functions so that they perform allocation up front before acquiring locks in order to reduce lock contention on the table locks, which are global and acquired in many other paths. This tends to simplify error handling also. I'm not sure how well that applies in this case, however. Certainly, we want to optimize for successful handling, since malloc(9) failure is very unusual and occurs only in very exceptional (and unfortunate) cases. A more likely failure is the exhaustion of the zone limit on the pcb zone, which gates the overall allocation of memory for the socket type, and should be the first memory type allocated when setting up pcbs for this reason. Robert N M Watson Computer Laboratory University of Cambridge
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