Re: Samba speed

[Richard Sharpe <rsharpe@richardsharpe.com>]

On Tue, 9 Dec 2008, Volker Lendecke wrote:

>> Is there a maximum stride size used by the redirector?  i.e., will it
>> use something bigger than 128k?  In any case, increasing the ext3
>> reservation window size should still be helpful.  It's OK if we
>> increase it to 32 blocks (128k, on a 4k block filesystem), and the
>> stride size is smaller than that.  But if it is often bigger than
>> 128k, then then it would probably be better if samba used the
>> EXT3_IOC_SETRSVSZ ioctl to dynamically set the reservation size as
>> appropriate.
>
> One might try to use "dd" from Cygwin on Windows. When I
> once analyzed this behaviour, the 1-byte writes were exactly
> at the end of the block the Win32 app gave to the kernel as
> seen by the sysinternals filemon tool.

Hmmm, I always thought the network behavior was to prevent the app from 
being given an ENOSPACE error when it closed the file and the OS tried to 
flush the cache only to find that there was no space remaining on the 
remote file system to actually perform the writes the local cache 
accepted.

However, this suggests that the behavior is the same for local and remote 
file systems.

I do believe, as Ronnie said and as your evidence suggests, that these 
writes are at the end of the IO written into the cache by the app.

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