Performance mismatch in get and put files!

[Richard Sharpe]

On 8 Oct 2003, Rajan Aggarwal wrote:

> Facing a weird behavior in "get" and "put" commands over samba.
> 
> I have 2 linux(RedHat 9.0) machines running samba2.2.8. Followed the
> following sequence of steps:
> 
> * [abc at localhost abc]$ smbclient //machine/test -U user -O TCP_NODELAY
> supplied the required password for "machine", which has the security
> type as "user"(i have an account on the remote machine).
> 
> * smb:\> put <filename>
> * Subsequently, tried smb:\> get <filename>
> 
> For the same file of any size greater than 32K, the speeds of transfer
> are different. There is a substantial difference of around 10K (speed of
> get being lesser). This difference goes on building up for larger files.
> 
> Though an entirely different protocol FTP, the speeds of transfer were
> exactly same(no ambiguities). But this ruled out the possibility of
> difference due to mismatch in machine configurations.
> 
> Could anyone provide a clue about it???

This could be explained by Samba using sendfile. I think the sendfile code 
was in 2.2.8.

Sendfile is used with read&X and means that data does not have to be 
copied from the file system to userspace and then back dow to the kernel 
to be sent over the wire.

Regards
-----
Richard Sharpe, rsharpe[at]ns.aus.com, rsharpe[at]samba.org, 
sharpe[at]ethereal.com, http://www.richardsharpe.com