[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: Where do you put your swap partition?

On Wed, Jan 23, 2008 at 02:21:28AM -0500, Rick Thomas wrote:
> On Jan 23, 2008, at 1:40 AM, Ron Johnson wrote:
> >Rick wrote
> >>On my own systems, I make swap huge (10 GB or more for 1 GB RAM --  
> >>Disk
> >>is cheap!) so I can mount /tmp on a tmpfs filesystem.
> >
> >Is this for apps that say "if malloc() fails, I create a tmp file"?
> > IOW, you pretty much ensure that malloc() will never fail?
> If you have /tmp on physical disk (e.g. an ext3 filesystem) the  
> process of opening a file for writing, writing it, closing it, re- 
> opening it for reading, reading it back in, closing it and deleting  
> it, hits the disk several times, even with a large buffer cache.  But  
> if that file is in a tmpfs filesystem and you've got enough ram, the  
> disk never gets involved.  If it's in a tmpfs filesystem but you  
> don't have enough ram, you have to swap, but you're no worse off than  
> you were with the disk-based filesystem.
> Given that logic, and the fact that tmpfs is limited by the size of  
> swap plus the size of ram, and the observation that disk is cheap and  
> getting cheaper, why not make swap as big as you're ever likely to want?

It also makes having an encrypted /tmp easy to set up.  Since /tmp gets
cleared on boot, it may as well start out empty.  Set up encrypted swap
and put /tmp on tmpfs.  Now they're both encrypted.


Reply to: