CVS commit: src/sys/net

[Jonathan Stone <jonathan%netbsd.org@localhost>]

Module Name:    src
Committed By:   jonathan
Date:           Wed Jan 21 22:15:16 UTC 2004

Modified Files:
        src/sys/net: bpf.c

Log Message:
Update bpf buffer parameters, as per recent discussion on tech-net.

Increase the default bpf buffer size used by naive apps that don't do
BIOCSBLEN, from 8k to 32k.  The former value of 8192 is too small to
hold a normal jumbo Ethernet frame (circa 9k), 16k is a little small
for Large-jumbo (~16k) frames supported by newer gigabit
Ethernet/10Gbe, so (somewhat arbitrarily) increase the default to 32k.

Increase the upper limit to which BIOSBLEN can raise bpf buffer-size
drastically, to 1 Mbyte.  State-of-the-art for packet capture circa
1999 was around 256k; savvy NetBSD developers now use 1 Mbyte.
Note that libpcap has been updated to do binary-search on BIOCSBLEN
values up to 1 Mbyte.

Work is in progress to make both values sysctl'able. Source comments
note that consensus on tech-net is that we should find some heuristic
to set the boot-time default values dynamically, based on system memory.


To generate a diff of this commit:
cvs rdiff -r1.86 -r1.87 src/sys/net/bpf.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.