[vdr] Re: Recordings menu sluggish - *the real* solution. :-)

[Carsten Koch <Carsten.Koch@icem.com>]

Stefan Huelswitt wrote:
...
> What a pitty we all have to patch the kernel to use this...
Yes. That's a big disadvantage.
I have SuSE's 2.4.20 installed on my vdr and I would not even want to
try to install the O_STREAMING patch.

O_DIRECT, on the other hand is pretty standard. For example, it also
exists in IRIX.

The advantage of O_STREAMING is that the required patch to vdr is trivial.

I agree with Andrew Morton's assesment on http://kerneltrap.org/node/view/460

----begin quote----
From: Andrew Morton
Subject: 2.5.42-mm1
To: linux-kernel
Date: 2002-10-11 22:50:02 PST

Robert Love wrote:
>
> ...
>
> Andrew, any experience on one vs. the other?

I'd say that if you were designing a new application which
streams large amount of data then yes, you would design it
to use O_DIRECT.  You would instantiate a separate IO worker
thread and a message passing mechanism so that thread would
pump your data for you, and would peform your readahead, etc.

If your filesystem supports O_DIRECT, of course.  Not all do.

The strength of O_STREAMING is that you can take an existing,
working, megahuge application and make it play better with the
VM by changing a single line of code.  No big redesign needed.
----end quote----


Carsten.



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