Re: [GIT PULL] Ext3 latency fixes

Lennart Sorensen
2009-04-06T21:50:36Z

On Sat, Apr 04, 2009 at 10:18:20PM +0200, Ingo Molnar wrote:
> btw., just to insert some hard data: usability studies place the
> acceptance threshold for delays to around 300 milliseconds.
>
> If the computer does not 'respond' (in a real or a fake, visible or
> audible way) to their input within 0.3 seconds they get annoyed
> emotionally.

You mean like hitting 'skip commercial' on the remote, and 2 minutes later
when the commercials are almost over, then it happens. Yeah users get a
bit peeved at that. Fortunately that particularly behaviour is somewhat
rare. 5 to 10 seconds is more common and sometimes it works fine.

> It does not matter how complex it is for the kernel to solve this
> problem, it does not matter how far away and difficult to access the
> data is. If we are not absolutely latency centric in Linux, if we
> spuriously delay apps that do supposedly simple-looking things the
> user _will_ get annoyed and _will_ pick another OS.

I would have to get _very_ annoyed before that happened. I would have
to find a less annoying OS to switch to as well.

> All things considered it is certainly a combined kernel and app
> problem space to get there, but not being completely aware of its
> importance in the kernel kills any chance of us ever having a
> long-term solution.

Certainly my problems are likely to a large extent mythtv's fault.

--
Len Sorensen