System documentation of Samba

Volker Lendecke Volker.Lendecke at SerNet.DE
Fri Sep 6 07:41:00 GMT 2002

On Thu, Sep 05, 2002 at 01:02:17PM -0400, David Collier-Brown wrote:
> 	It doesn't affect the performance of Samba on
> 	Solaris in general, and oddly enough it doesn't
> 	seem to hit MS Access... 

Sorry, David, but that description is not completely correct. The Solaris fcntl
scaling problem does *not* happen on files that are shared to users, it happens
on the internal Samba .tdb-files. They have a dbm-like API, but they only use
one file. The problem is that many processes might be waiting for an fcntl
write lock, or have fcntl read locks on for example the connections.tdb. When
many processes are waiting, and the lock becomes free, all of them are
scheduled to run. At least that is Tridge's analysis. So given enough processes
you get a thundering herd problem upon freeing a fcntl lock.


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