Re: [Tracker] [Re: tracker in F16]

[Lennart Poettering <mztabzr 0pointer de>]

On Tue, 20.09.11 09:49, Martyn Russell (martyn lanedo com) wrote:

> > a) tracker uses inotify recursively and creates a massive number of
> > watches due to that. That is both ugly and doesn't scale. Tracker
> > apparently tries to not take up the full pool of inotfy handles the
> > system provides, but that won't help if you have more than one user on
>
> Yes, this sucks enormously. When we have a clean shutdown (i.e. no
> work is being done and we know we're up to date), we can start up
> with n thousand directories being monitored in < 60 seconds with
> thousands of directories being crawled under cold cache. Again this
> depends a little on the hardware and the number of directories, but
> it's damn fast. It also shouldn't be that noticeable. Aleksander has
> had some ideas about how to avoid this entirely, but then it's a
> question of user space vs kernel space. I will let him comment
> further here.

60s of disk access is actually quite a lot. We can boot userspace in <
1s now, 60s of disk access afterwards due to tracker are actually really
awful.

> > the system. The solution here should probably be fanotify, which allows
> > proper recursive file system watches. So far fanotify has been
> > accessible to root only, which is presumably why tracker doesn't use
> > it. However, the solution here cannot be to work around that fact by
> > using inotify, but must be to invest the necessary kernel work to make
> > fanotify useful from unprivileged processes.
>
> Yes, we were looking on at Eric Paris' work with high expectations,
> but from what we've discussed internally as a team, it doesn't look
> to improve our situation nearly enough and really would just assist
> us (from what I remember). Again Aleksander can comment on this.

The thing is that the kernel is fixable. If it's borked fix it, don't
work around it. It's C code, like userspace too. It's free, like
userspace is. Tracker is not an island. We as the community own the
stack from top to bottom, so we can fix it top to bottom. That's what
makes us better than Windows.

Lennart

-- 
Lennart Poettering - Red Hat, Inc.