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SubjectRe: Throughput @100Mbs on link of ~10ms latency
On Thu, 4 Oct 2001, Ben Greear wrote:

> printAndExec("echo $rmem_default > /proc/sys/net/core/rmem_default");
> printAndExec("echo $netdev_max_backlog > /proc/sys/net/core/netdev_max_backlog");
>

... thanks -

tried these parameters and saw no change in the throughput. I am
thinking that the problem is at the receiving end rather than the transmit
end because with the FreeBSD machine at 1 end I got a much higher
throughput when sending to that machine. (about 10 MBytes /sec)

I was suspicious of another problem with the FreeBSD machine which is why
I changed it out. (network occasionally locked up). The distance between
the local ethernet switches is about 1200km of fibre. Speed of light for
that distance is ~ 4ms. Light in fibre I believe to be about 0.6 giving
around 6.5ms for light in this loop - so 9.5 ms RTT seems pretty good

The machines (Compaq Deskpro ~800MHz) are able to reliably produce
~10MBytes/sec using ncftp which is hardly calibrated but is atleast
indicative of the rate I should be getting. Calculating transfer time of
26/27 secs of 106348240 gives me net of about 32Mbps

anyway thanks for your help

cheers
Mark


one machine is:

eth1 Link encap:Ethernet HWaddr 00:04:76:B8:8B:DC
inet addr:192.168.1.1 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:11757991 errors:0 dropped:0 overruns:1 frame:0
TX packets:11699364 errors:0 dropped:0 overruns:0 carrier:49
collisions:274 txqueuelen:100
Interrupt:5 Base address:0x1000

eth1: 3Com PCI 3cSOHO100-TX Hurricane at 0x1000, 00:04:76:b8:8b:dc, IRQ 5
product code 4d4d rev 00.12 date 06-29-01
8K byte-wide RAM 5:3 Rx:Tx split, autoselect/Autonegotiate interface.
MII transceiver found at address 24, status 7849.
Enabling bus-master transmits and whole-frame receives.
eth1: scatter/gather disabled. h/w checksums enabled
eth1: using NWAY device table, not 8

the second is:

eth1 Link encap:Ethernet HWaddr 00:01:03:39:ED:5F
inet addr:192.168.1.3 Bcast:192.168.1.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:9567005 errors:0 dropped:0 overruns:0 frame:0
TX packets:9652682 errors:0 dropped:0 overruns:0 carrier:607
collisions:0 txqueuelen:100
Interrupt:5 Base address:0x1000

eth1: 3Com PCI 3c980 10/100 Base-TX NIC(Python-T) at 0x1000,
00:01:03:39:ed:5f, IRQ 5
product code 4b50 rev 00.14 date 03-12-01
8K byte-wide RAM 5:3 Rx:Tx split, autoselect/Autonegotiate interface.
MII transceiver found at address 24, status 7809.
Enabling bus-master transmits and whole-frame receives.

>
> And of course, make sure you can get the performance with a known fast network
> (and near zero latency) first!!
>
> The e100 has some interesting options that seem to make it handle high packet
> counts better, as well as giving it bigger descriptor lists, but I haven't
> really benchmarked it..
>
> Ben
>
>


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