Re: pin files in memory after read

[Arjan van de Ven <arjan@infradead.org>]

On Mon, 2005-01-03 at 19:07 +0100, Olaf Hering wrote:
> Is there a way to always keep a file (once read from disk) in memory, no
> matter how much memory pressure exists?
> There are always complains that updatedb and similar tools wipe out all
> caches. So I guess there is no such thing yet.
> 
> I simply want to avoid the spinup of my ibook harddisk when something
> has been 'forgotten' and must be loaded again (like opening a new screen
> window after a while).
> 
> The best I could do so far was a cramfs image. I copied it to tmpfs
> during early boot, then mount -o bind every cramfs file over the real
> binary on disk. Of course that will fail as soon as I want to update an
> affected package because the binary is busy (readonly). So there must be
> a better way to achieve this.
> 
> How can one tell the kernel to pin a file in memory once it was read?
> Maybe with an xattr or something?
> Unfortunately I dont know about the block layer and other things
> involved, so I cant attach a patch that does what I want.

you could write a small userspace daemon that mmaps the file and mlock's
it....