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  • From: sindi keesan <keesan AT sdf.lonestar.org>
  • To: baslinux AT lists.ibiblio.org
  • Subject: Re: [BL] serial networking and telnet server
  • Date: Wed, 8 Dec 2004 23:17:17 +0000 (UTC)

With swap file unzipped and activated (I rebooted) it took 2 min to pkg links2.tgz (and 4 min to transfer it - 2MB, or about 7K/sec).
The HD light came on often during the unzipping process.

I think my slow kermit transfer might be related to the lack of swap file earlier.

Kermit took 35 sec to load the first time, 15 the second time (from buffer). Links2 loaded in 15 sec first time 5 sec second time. So this computer is usable in CLI mode for BL3.

When I first tried to set up serial networking both computers told me 'network is unreachable'. I switched to 19200 for the desktop and it then started to ping itselfand the laptop, then I gradually went back up to 115200 and it continued to work and I sent. I then went online (pppd for modem) and then tried again to use serial networking and since then 'network is unreachable' even after rebooting, turning computer off and on, going from BL3 to BL2. Llpro worked over the serial cable after this.
The laptop continued to ping itself.

I turned the laptop off and on and rebooted linux and now pppd won't work there either with nullmodem cable.

WHat stupid thing might I have done or be doing?

pppd local crtscts clark:lois 115200 /dev/ttyS0
(on the other computer lois:clark and /dev/ttyS2)

I wanted to test whether the swap file speeded up file transfer.

On Wed, 8 Dec 2004, sindi keesan wrote:
I have a serial connection set up between Bl3 on a pentium desktop and Bl3 on a 386 SX20 with 387, and 5MB RAM. To test it I used send/receive to send the kermit binary, about 2MB file. It took roughly 25 minutes.

At 9K/sec, 2,000,000/9,000 = 222 seconds, or under 4 minutes.
If the file were compressed first it would be 1/3 as long (I tried gzipping it), or about 1 minute transfer time.

This implies that the tar/untar part of send/receive took about 24
minutes. Tar at the pentium end is nearly instant (128MB RAM, 233MHz cpu), so it is slowing things down on the 386.

I was able to transfer after setting up pppd at 115200 (it pinged okay but the test packet took 110 mseconds, whereas ethernet ping is something like .3 ms, or I may be wrong but it is much faster anyway. The speed ratio of 110 to .3 is about 330, and that below about 800, but there is some overhead involved as well).

Based on previous experience transferring the entire linux setup from one drive to another via ethernet, the slowest part of the process is gzipping the large .tar file.

Serial transfer is about 10K/sec,
ethernet 1-10MB/sec
parallel was in between (1/40 of ethernet = 250K, 8x serial = 80K?)

I get the following:
serial: 9K/sec @115200
I was rounding.
ethernet: 700K/sec
That is 10MBit ethernet. The 100MBit is ten times as fast in theory.

plip: 38K/sec


Anyway, I think it would be faster, when one of the computers involved is a 386 with 5MB RAM, not to tar/untar during the send process.

It took about 5 minutes (guessing) to unzip the swap.zip file using linux during the file transfer. I think unzip or gunzip might run faster if not done during transfer when there is not much memory, but it still might be better to avoid using zip on a slow computer.

How would I modify these scripts to send/receive uncompressed files? I could then gunzip the .tgz file, transfer the .tar file, and just untar (which is much faster) on the 386 target. Will pkg work on .tar as opposed to .tgz files? Or I can manually tar -xvf on / and run the install script.

I am thinking of transferring links2 binary that way. The rest of the packages are small enough to transfer via floppy disk (not counting abiword, which won't work on the 386 anyway, nor will other X programs, at a reasonable speed). I can also split up links2 binary to two floppy disks. But not all laptop computers still have working floppy drives.

I was hunting through the old emails looking for Steven's script to use netcat to send a .tgz package and untar it automatically with the receive script and not save the .tgz package and cannot find it, nor can google. Someone please steer me to it, thanks. I copied it to some place safe....
But I think sending an uncompressed file might work better here.

The 386 cursor problem disappeared when we put in a working backlight. The linux cursor seems to be harder to see than the DOS cursor.

A 386 with 5M is hardly ideal even for CLI. Kermit took about 36 sec to reload. It is taking nearly as long to exit. (Maybe next time I boot linux with swap file it will go faster?).
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