Win2K/XP, oplocks, and readahead

Peter Godman pete at
Fri Feb 21 18:43:58 GMT 2003

Hi there!

Although I am most focused on Windows clients since that is what our
customers use, this would be a great thing to try to attempt to exonerate
samba (not that much suspicion lies there anyway :)).  It would be an
interesting data point.  I can't believe that I can't find *any*
information about someone doing this sort of workload over CIFS with
Windows clients!

Thanks for the advice!

Peter Godman

On Fri, 21 Feb 2003, Steven French wrote:

> The readahead that the Linux page manager does (see mm/readahead.c) seems
> more sensible than what you are seeing with the Windows client - if you are
> trying to excercise your server in this way you might try the clients using
> the current version of Linux 2.5 kernel mounted with the cifs vfs or smbfs
> to your Samba server - this is probably a much more efficient way to
> exercise readahead using SMB clients.  The algorithm used by the Linux page
> manager for readahead is pretty interesting.   Note (if writebehind is also
> being tested) that in the current 2.5 kernel implementation of the cifs vfs
> at the moment there is a call missing to flush at oplock break time and
> also at sync time (flush is called properly at file close time) but this
> should be fixed soon.
> Steve French
> Senior Software Engineer
> Linux Technology Center - IBM Austin
> phone: 512-838-2294
> email: sfrench at

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