Am 06.06.2015 um 05:06 schrieb Dennis Jacobfeuerborn:
That's true but it also means that if you lock that page so it cannot be swapped out then this page is not available for the page cache so you incur the i/o hit either way and it's probably going to be worse because the system has no longer an option to optimize the memory management. I wouldn't worry about it until there's actually permanent swap activity going on and then you have to decide if you want to add more ram to the system or maybe find a way to tell e.g. Bacula to use direct i/o and not pollute the page cache. For application that do not allow to specify this a wrapper could be used such as this one: http://arighi.blogspot.de/2007/04/how-to-bypass-buffer-cache-in-linux.html
Actually I found better links: https://code.google.com/p/pagecache-mangagement/ http://lwn.net/Articles/224653/
"It is to address the "waah, backups fill my memory with pagecache" and the "waah, updatedb swapped everything out" and the "waah, copying a DVD gobbled all my memory" problems."
Dennis, thanks for the links. I hope to get around using these tools. But it's good to have them in my "arsenal" ;)
Cheers, Shorty