Re: Building off Medusa

[Alexander Larsson <alexl redhat com>]

On Mon, 14 Apr 2003, Manuel Amador (Rudd-O) wrote:

> >FAM does not support recursive monitoring, which means you have to add a
> >monitor for every directory to receive notification of changes to those
> >files. According to the FAM FAQ, you can only have 1024 active
> >"requests", which means you can only monitor up to 1024 directories. My
> >computer has more than 30000 directories... so I don't see how it would
> >be possible to use FAM to receive notification of changes across my
> >whole filesystem.
> >
> >-Seth
> >
> Well, I don't know about your experience in FAM's regard, but I can 
> assure you I have monitored thousands of directories without problem.  I 
> don't care if it was using dnotify or not, I just used the command-line 
> notification tool which is in SGI's OSS projects web site, and it 
> worked.  And it didn't have any noticeable performance impact.
> 
> Thousands.  I have the feeling that FAM does NOT open each directory to 
> be monitored. I would understand your concerns if it did

I you're using the dnotify version if FAM it *does* open each directory. I 
should know, since I wrote that code. If you're using imon it doesn't, but 
then you need to patch your kernel. If you're not using either of them 
you're polling, which indeed doesn't open each directory, but has resource 
utilization problems (polling thousands of directories every few 
seconds? No thanks).

-- 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
 Alexander Larsson                                            Red Hat, Inc 
                   alexl redhat com    alla lysator liu se 
He's a shy one-eyed dwarf with a mysterious suitcase handcuffed to his arm. 
She's a man-hating goth snake charmer from Mars. They fight crime!