Re: [UPDATE] Fresh zerocopy patch on kernel.org

Malcolm Beattie
2001-01-31T15:27:31Z

David S. Miller writes:
>
> At the usual place:
>
> ftp://ftp.kernel.org/pub/linux/kernel/people/davem/zerocopy-2.4.1-1.diff.gz

Hmm, disappointing results here; maybe I've missed something.

Setup is a Pentium II 350MHz (tusk) connected to a Pentium III
733MHz (heffalump) (both 512MB RAM) with SX fibre, each with a
3Com 3C985 NIC. Kernels compared are 2.4.1 and 2.4.1+zc
(the 2.4.1-1 diff above) using acenic driver with MTU set to 9000.
Sysctls set are
# Raise socket buffer limits
net.core.rmem_max = 262144
net.core.wmem_max = 262144
# Increase TCP write memory
net.ipv4.tcp_wmem = 100000 100000 100000
on both sides.

Comparison tests done were
gensink4: 10485760 (10MB) buffer size, 262144 (256K) socket buffer
ftp: server does sendfile() from a 300MB file in page cache,
client does read from socket/write to /dev/null in 4K chunks.

2.4.1 2.4.1+zc
KByte/s tusk%CPU heff%CPU KByte/s tusk%CPU heff%CPU
gensink4
tusk->heffalump 94000 58-100 93 54000 98-102 11-45
heffalump->tusk 72000 86-100 46-59 70000 71-93 53-71

2.4.1 2.4.1+zc
KByte/s KByte/s
ftp heffalump->tusk 86000 62000

I was impressed with the raw 2.4.1 figures and hoped to be even more
impressed with the 2.4.1+zc numbers. Is there something I'm missing or
can change or do to help to improve matters or track down potential
problems?

--Malcolm

--
Malcolm Beattie <mbeattie@sable.ox.ac.uk>
Unix Systems Programmer
Oxford University Computing Services