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RE: network throughput
I also has some concerns regarding the netwok performance, so I made
a simple network/memory bechmark utility tcp_perf.c (you can find it in
devboard_lx/tools/src/tcptest). It works both on Linux and Windows.
Here are results for devboard:
Test 1 (devboard TCP server, Linux PC client)
[root@AxisZoka /]49# tcp_perf -s 5000 1000000
Waiting for client connection
Accepted client connection
Time to receive 100000000 bytes was 30160 msec (3315600 bytes/sec)
3300 recv() calls made, average CPU load during transfer 98% (S:98% U:0%)
[firstname.lastname@example.org 5000 10000000 1000000
Connecting to 192.168.0.99:5000...
Connected to 192.168.0.99!
10000000 bytes sent to 192.168.0.99 10 send() calls made
Test 2 (devboard UDP server, Linux PC client)
[root@AxisZoka /]49# tcp_perf -us 5000
Time to receive 10000000 bytes was 3220 msec (3105500 bytes/sec)
7143 packets received, average CPU load during transfer 96% (S:94% U:2%)
[email@example.com 5000 10000000 1400
10000000 bytes sent to 192.168.0.99 in 7143 packets
Note that UDP server has to be started before the client, otherwise the
handshake mechanism will fail.
Johan Adolfsson did some tests for me on 16-bit wide SDRAM:
Time to receive 10000000 bytes was 2200 msec (4545400 bytes/sec)
336 recv() calls made, average CPU load during transfer 77% (S:77% U:0%)
> -----Original Message-----
> From: firstname.lastname@example.org]On">mailto:email@example.com]On
> Behalf Of Akshay Adhikari
> Sent: Saturday, 24 August 2002 02:15
> To: Mikael Starvik
> Cc: firstname.lastname@example.org
> Subject: RE: network throughput
> Thanks for the help... however, my numbers using netperf are inconsistent
> with yours, and there are some other problems/questions I have:
> I am using kernel 2.4.14.
> - with netperf, TCP achieved at most 12-15 Mbits/s (when the
> receiver was a devbaord, and the sender was either a devboard or a PIII).
> - with netperf, sending UDP packets of sizes in the range 100-500
> bytes, spaced about 1ms apart cause ethernet overruns very quickly on the
> receiver box. For example, sending 250 byte UDP packets, one every 1 ms
> from one devboard to another for a period of 20 seconds gave these
> packets sent: 19187
> packets rcvd: 3412
> all dropped packets were overruns on the receiver box.
> This behavior is also inconsistent- it happens for a wide
> range of packet sizes and interpacket spacing.
> When this happens, the box sometimes freezes: here is part of a message
> I get from the kernel:
> Unable to handle kernel access at virtual address 20000000
> Oops: 0000
> 60068bd8 SRP: 600689be DCCR: 000004a0 USP: 4ffffd84 MOF: 00000000
> r0: 00000200
> r1: b00
> another strange thing: after the box freezes, if I reboot it by pressing
> the reboot button,
> it negotiates
> half-duplex mode with the switch it is connected to. On the other hand,
> if I reboot it by _powering off_, it negotiates ful duplex.
> any idea why this might happen?
> - Since the acheived throughput is surprisingly low, I'm trying to locate
> possible sources of bottlenecks - card to OS DMA transfer because of slow
> mem. access time, or simply the overhead of calling recv() repeatedly from
> user space, etc....
> any suggestions towards improving the performance by just OS tweaks rather
> than hardware changes would be great!
> On Fri, 23 Aug 2002, Mikael Starvik wrote:
> > Hi,
> > If I remember it correctly the performance with a developer
> > board LX is approximately 4 MBytes/s for receive and 3 MByte/s
> > for transmit (with the latest kernel). With other memory
> > configurations you can get 5 MByte/s (receive) and 4 MByte/s
> > (transmit).
> > >- data bus width (32 bit??)
> > On the developer board LX the data bus width is 16 bits.
> > With 32 bits and SDRAMs you can get higher performance.
> > >- data bus speed
> > 50 MHz
> > >- dma setup latency
> > I don't know the typical latency. It depends a lot on what
> > else is going on in the system (although the ethernet DMAs
> > have very high priority)
> > >- size of network rx buffers (32KB??)
> > 64 full size packets
> > >- maybe typical interrupt latency....
> > I don't know.
> > /Mikel
> > -----Original Message-----
> > From: email@example.com]On">mailto:firstname.lastname@example.org]On
> > Behalf Of Akshay Adhikari
> > Sent: Thursday, August 22, 2002 3:55 PM
> > To: dev-etrax
> > Subject: network throughput
> > hello,
> > I would like to find out the max achievable network throughput on a
> > devboard_lx (For example, in experiments with netperf, I found that tcp
> > throughput was atmost 15 Mbps, and sending UDP packets back to back
> > caused receiver overruns pretty fast...)
> > I was trying to find the specifications for the devboard_lx to use for
> > calculations of
> > max. achievable data throughput; it would be useful to know:
> > - data bus width (32 bit??)
> > - data bus speed
> > - dma setup latency
> > - size of network rx buffers (32KB??)
> > - maybe typical interrupt latency....
> > does anyone have these numbers or know how/where to obtain them?
> > TIA,
> > akshay