Date: Wed, 5 Dec 2007 09:50:40 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: Vlad GALU <dudu@dudu.ro> Cc: freebsd-net@freebsd.org, Peter Losher <Peter_Losher@isc.org> Subject: Re: Aggregating many ports into one for tcpdump server. Message-ID: <20071205094657.P87930@fledge.watson.org> In-Reply-To: <20071205093244.U87930@fledge.watson.org> References: <4755EFDD.8070609@isc.org> <20071205021851.V87930@fledge.watson.org> <ad79ad6b0712050100p90a1917w5440e06a94f816e7@mail.gmail.com> <20071205093244.U87930@fledge.watson.org>
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On Wed, 5 Dec 2007, Robert Watson wrote: > On Wed, 5 Dec 2007, Vlad GALU wrote: > >> I would like to try the aforementioned patches too. Can you please point me >> to a link? > > You can download our experimental tarball from here: > > http://www.watson.org/~robert/freebsd/20071103-zcopybpf.tgz > > You can find a BSDCan quick talk on the topic here: > > http://www.watson.org/~robert/freebsd/2007bsdcan/20070517-devsummit-zerocopybpf.pdf > > I've had several reports of significantly improved packet capture rates at > high speeds with it, but it's not yet in the tree because we feel it needs > more evaluation and review. I hope to ship some form of zero-copy BPF > buffer support in FreeBSD 8, and possibly even MFC it. Any feedback you > might have would be most helpful. Having sent you the patch, I should have let you know that you'll need to: - Add options BPF_ZEROCOPY to your kernel configuration to enable the zero-copy buffering mode. - Make sure the kernel and libpcap are rebuild following the application of the patch and dropping in the tarball. - setenv BPF_ZERO_COPY before running tcpdump or other BPF-based tools to enable the zero-copy buffer mode. The patch includes both kernel changes (abstract the buffer model, add a new buffer model) and user space changes (updated libpcap to speak the new model, selected right now with the environmental variable). Presumably if merged, zero-copy BPF buffers would be used by default via libpcap if present in the kernel, but right now this is all for evaluation purposes. Robert N M Watson Computer Laboratory University of Cambridge
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