Re: userspace pagecache management tool

Andrew Morton
2007-03-03T21:12:15Z

On Sat, 03 Mar 2007 15:40:42 -0500 Rik van Riel <riel@redhat.com> wrote:

> Andrew Morton wrote:
>
> > 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.
>
> By removing pressure from the page cache, you'll only allow updatedb
> to grow the inode and dentry caches larger than before.

Well duh.

That's a two-order-of-magnitude lesser problem and only affects one of many
problematic workloads.

> I am sick and tired of the "this is hard, let userspace do it" attitude.

Anything you try to do in-kernel will catastrophically screw up some
workloads. You don't have a chance of getting this right.

You are the kernel. The user just read an entire kernel tree. You face a
binary decision: do you cache that tree or do you not? Your time starts
now. What is your answer?