Re: Help with slow transfers from pc to pc
From: Allen Kistler (ackistler_at_yahoo.com)
Date: 07/29/03
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Date: Tue, 29 Jul 2003 05:52:09 GMT
Nick Austin wrote:
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> On Sun, 27 Jul 2003 22:14:05 +0000, Allen Kistler wrote:
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>
>>Conclusion: I blame the ftp server software. WU-ftpd, Proftpd, vsftpd,
>>all are the same. So I use scp and get 10x the throughput. Silly that
>>scp, which has lots more overhead in terms of protocol and its cpu
>>requirement, should be faster, but it's true.
>
>
> What draws you to that conclusion?
>
The parts of my previous post that you chose to snip lead me to that
conclusion. Sorry to be short, but if any of the things you suggested
were true, I wouldn't be able to fill up the pipe using scp (which you
didn't snip). As I said, ONLY ftp servers on ONLY Linux are slow.
Linux or Windows (various) or Solaris (7) or OS/2 clients and Windows or
Solaris or OS/2 servers have no problem. EVERYTHING else (including,
but not limited to, every other data transfer program on Linux) fills up
the pipe, near 100% bandwidth utilization, less than 0.1% retries for
collisions. But since you asked, stats for two systems at opposite ends
of the performance spectrum (486 transmitter, 686 receiver) indicate no
problems, even though ttcp only got 78% utilization. BTW, 0 errors, 0
dropped.
ttcp-r: 16777216 bytes in 20.99 real seconds = 780.62 KB/sec +++
ttcp-r: 12286 I/O calls, msec/call = 1.75, calls/sec = 585.37
ttcp-r: 0.0user 0.5sys 0:20real 2% 0i+0d 0maxrss 0+1pf 0+0csw
ttcp-t: 16777216 bytes in 20.97 real seconds = 781.32 KB/sec +++
ttcp-t: 2048 I/O calls, msec/call = 10.48, calls/sec = 97.67
ttcp-t: 0.0user 4.5sys 0:20real 21% 0i+0d 0maxrss 0+2pf 0+0csw
Linux ftp servers get 10 KB/sec to 20 KB/sec with cpu utilization too
small to show up in top. Tests of SCSI disk throughput with and without
blocksizes greater than the buffer sizes get 7 MB/sec to 18 MB/sec. Not
the cpu. Not the disk. Not the network. Must be the software,
especially when other software on the same hardware/OS platform has no
problem.
I'm more bothered that there are no ready answers than the inability to
make any ftp server perform (but only on Linux, since I have other OSes
that run ftp services fine). Meanwhile I use anything but Linux ftp
services, other Linux services being fine, too.
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