Use of mmap in Samba 3
jra at samba.org
Thu Mar 27 23:40:31 GMT 2008
On Thu, Mar 27, 2008 at 05:03:25PM -0600, Cam Macdonell wrote:
> I am curious if there are any circumstances under which a Samba Server
> would mmap a file. I did a quick search through the code and most uses
> of mmap seem to point to tdb and ldb. Is mmap used for the databases or
> are files ever mmaped? Such as for better performance.
> If found the following comment in source/lib/replace/test/shared_mmap.c:
> /* this tests whether we can use a shared writeable mmap on a file -
> as needed for the mmap variant of FAST_SHARE_MODES */
> as well as the smb.conf parameter "use mmap" but it refers to debugging
> tdb code.
> However, I wasn't able to find any more information in the documentation.
We used to do this (in Samba < 3.0), but the problem comes with dealing with the signals
if another application truncates the mmap'ed region whilst it's active.
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