sftp from home wireless box to work - get is much faster that put

[Anton Shterenlikht]

I was trying to measure the file transfer
rates between my home and my office boxes.
Both are 9.0-current.

At home I've wireless, TL-WN851N, using ath(4) driver.

I used sftp(1), which I launch from the home box.

I made files sized 10MB, 100MB and 1GB via

dd if=/dev/zero of=/home/mexas/1gb bs=1m count=10
dd if=/dev/zero of=/home/mexas/1gb bs=1m count=100
dd if=/dev/zero of=/home/mexas/1gb bs=1m count=1024

respectively.

What I discovered is put(mput) is much slower than get(mget).

Here is a sample of timings:

10MB file
#########

sftp> put 1gb
Uploading 1gb to /usr/home/mexas/1gb
1gb					100%   10MB  59.2KB/s   02:53    
sftp> mget 1gb
Fetching /usr/home/mexas/1gb to 1gb
/usr/home/mexas/1gb			100%   10MB 330.3KB/s   00:31    

100MB file
##########

sftp> mput 1gb
Uploading 1gb to /usr/home/mexas/1gb
1gb					100%  100MB  58.6KB/s   29:07    
sftp> mget 1gb
Fetching /usr/home/mexas/1gb to 1gb
/usr/home/mexas/1gb			100%  100MB   1.0MB/s   01:41    
sftp> mget 1gb
Fetching /usr/home/mexas/1gb to 1gb
/usr/home/mexas/1gb			100%  100MB 930.9KB/s   01:50    

1GB file
########

sftp> mget 1gb
Fetching /usr/home/mexas/1gb to 1gb
/usr/home/mexas/1gb			100% 1024MB 796.8KB/s   21:56    
sftp> mput 1gb
Uploading 1gb to /usr/home/mexas/1gb
1gb					7%   79MB  56.3KB/s 4:46:28 ETA

(I interrupted the last transfer, just too long to wait).

So putting (sending) a file is about 5-17 times faster
than getting (receiving) it.

What is the reason behind this?  

many thanks
anton

-- 
Anton Shterenlikht
Room 2.6, Queen's Building
Mech Eng Dept
Bristol University
University Walk, Bristol BS8 1TR, UK
Tel: +44 (0)117 331 5944
Fax: +44 (0)117 929 4423