Date: Mon, 24 Mar 2008 14:15:51 +0000 (GMT) From: Robert Watson <rwatson@FreeBSD.org> To: "Christian S.J. Peron" <csjp@FreeBSD.org> Cc: arch@freebsd.org, freebsd-current@freebsd.org, net@freebsd.org Subject: Re: HEADS UP: zerocopy bpf commits impending Message-ID: <20080324141334.T7797@fledge.watson.org> In-Reply-To: <20080324140623.GA14941@sub.vaned.net> References: <20080317133029.GA19369@sub.vaned.net> <20080317134335.A3253@fledge.watson.org> <20080324140623.GA14941@sub.vaned.net>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, 24 Mar 2008, Christian S.J. Peron wrote: > I just want everyone to know that I have completed the zerocopy bpf commit. > Please be on the "lookout" for any strange bpf related issues. > > For people that want to test the new zerocopy bpf implementation, a patch > can be found here: > > http://people.freebsd.org/~csjp/pcap.1206364304.diff > > Any comments, patches etc can be sent to Robert Watson (rwatson@) or myself. FYI, right now there is a known issue in which only one of the two BPF buffers can be owned by user processes at a time. As a result, when acking one buffer, it's almost always the case that userspace will enter select() even though another buffer is essentially ready, leading to a system call being generated for each buffer even though that's undesirable. I'm working on some changing allowing both buffers to be owned by userspace at a time, but it will be a couple of weeks before that enters CVS. I believe that the current libpcap patches should keep working with that fine, although of course, we'll see. :-) The bpf.4 documentation is very careful to warn that applications should not assume that there are any invariants about the number of buffers assigned to userspace at a time. Robert N M Watson Computer Laboratory University of Cambridge
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20080324141334.T7797>