Re: Linux kernel impact on PostgreSQL performance

On Wed, Jan 15, 2014 at 5:34 AM, Jim Nasby <jim@nasby.net> wrote:
> it's very common to create temporary file data that will never, ever, ever
> actually NEED to hit disk. Where I work being able to tell the kernel to
> avoid flushing those files unless the kernel thinks it's got better things
> to do with that memory would be EXTREMELY valuable

Windows has the FILE_ATTRIBUTE_TEMPORARY flag for this purpose.

ISTR that there was discussion about implementing something analogous
in Linux when ext4 got delayed allocation support, but I don't think
it got anywhere and I can't find the discussion now. I think the
proposed interface was to create and then unlink the file immediately,
which serves as a hint that the application doesn't care about
persistence.

Postgres is far from being the only application that wants this; many
people resort to tmpfs because of this:
https://lwn.net/Articles/499410/

Regards,
Marti