[CentOS] Effectiveness of CentOS vm.swappiness

Sat Jun 6 09:25:29 UTC 2015
Markus "Shorty" Uckelmann <shorty at koeln.de>

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