[mythtv-users] My MythTV journey

[Brian Scully]

 --- On Tue 12/23, David Rees < drees at greenhydrant.com > wrote:
From: David Rees [mailto: drees at greenhydrant.com]
To: mythtv-users at mythtv.org
Date: Tue, 23 Dec 2003 17:58:31 -0800 (PST)
Subject: Re: [mythtv-users] My MythTV journey

On Tue, December 23, 2003 at 5:51 pm, Brian Scully wrote:
>> I'm not sure why swap is being used then. I'm no kernel hacker, but it
>> seems strange that you would allow your cache to swap to disk - what 
>> performance benefit are you getting? BTW i'm up to 21 MB of swap used now.

> Linux will start swapping programs out to disk which haven't been used in
> a while to make more room for filesystem cache.  Even if you have
> gigabytes of memory in your machine, if you do a lot of work with large
> files which exceed the amount of memory in the machine, the kernel will
> start swapping some things out to improve performance.

Agreed.  Jarod was suggesting that the kernel cached as much as possible
from disk reads to improve performance.  The swapfile is on the disk.  My
question was: if it is in fact the kernel's cache that is filling my memory,
Why would the kernel maintain that information on disk to save it from being
read from disk?  That was my original question.  So maybe, as you're saying,
there's something else that runs (maybe userspace) that eats all of this 
memory.  Incidentally, as this thread has run its course, the backend crashed
and I now am using only 98MB of ram ( and 51 MB of swap ).

In a semi-related vein, I am considering applying steve at nexusuk.org's O_STREAMING patch and building mythtv from scratch.  Has anyone tried this one out yet?  It looks like it would affect how much memory that the backend eats for streaming videos.

Brian

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