Date: Tue, 5 Aug 2003 14:01:32 -0700 (PDT) From: John Polstra <jdp@polstra.com> To: net@freebsd.org Subject: Re: bpf, ipfw and before-and-after Message-ID: <200308052101.h75L1WR1006787@strings.polstra.com> In-Reply-To: <01ca01c35b86$83c75590$812a40c1@PETEX31> References: <20030805133922.GA7713@k7.mavetju> <200308051817.h75IH7jb006622@strings.polstra.com> <01ca01c35b86$83c75590$812a40c1@PETEX31>
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In article <01ca01c35b86$83c75590$812a40c1@PETEX31>, Petri Helenius <pete@he.iki.fi> wrote: > > > > This would add additional delays to the code path for both ingress > > and egress. In a world where gigabit ethernet is becoming the norm, > > every nanosecond counts. I don't think the benefits of your proposal > > would justify the performance loss. At the very least, I'd want the > > extra calls to bpf_mtap to be present in the code only if enabled by > > an option in the kernel config file. > > > bpf is slow by design because the design mandates a packet copy. > > Itīs not a justification to make it slower but gigabit performance out of bpf > is just not there until memory speeds increase a lot or the copying goes away. My point is that the extra calls to bpf_mtap would harm performance even when bpf wasn't being used. John -- John Polstra John D. Polstra & Co., Inc. Seattle, Washington USA "Two buttocks cannot avoid friction." -- Malawi saying
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