[mythtv-users] Best way to integrate a Netflix feed into Myth ?

Eric Sharkey eric at lisaneric.org
Tue Aug 23 18:32:03 UTC 2011

On Mon, Aug 22, 2011 at 6:55 PM, Raymond Wagner <raymond at wagnerrp.com> wrote:
> Linux has a great disk cache.  Anything you store to disk gets stored in
> cache, until such time as something else flushes it out.  The more memory
> you have, the longer it takes to get flushed out.

Sort of.  The latency of writing dirty ram pages representing file
data to disk doesn't really depend on the amount of ram you have.
There are a whole bunch of tuning parameters that control this
(usually configured by the distro in /etc/sysctl.conf) but it's common
to make sure that writes to the disk actually get written out to the
disk within ~5 seconds.  That's the first half of getting flushed out.
 The second half of getting flushed out is when the kernel decides it
has a better use for the page and drops the information.  This second
part will be delayed if there's a lot of ram available, but when
you're dealing with fundamentally temporary data, it makes no sense to
have this information backed by a file in the file system, as it just
adds writes to the disk for data that will never be read.  You can use
a tmpfs for this sort of thing if you really want a file I/O api, but
again that seems unnecessary here.

I'm sure those of us with longer memories remember that mythTV did
have a plugin that was meant to allow interacting with low latency
real time video feeds.  It was called mythPhone.  This hasn't been
maintained, but someday I'd like to see this come back, too.  It's
basically the same problem.


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