[mythtv-users] Dual-FireWire troubles in 0.20 solution found

Jim Westfall jwestfall at surrealistic.net
Sat Sep 16 00:49:05 UTC 2006

Michael T. Dean <mtdean at thirdcontact.com> wrote [09.15.06]:
> On 09/15/06 17:07, Yeechang Lee wrote:
> >
> >* 0.19 did not have this issue.
> >* 0.20 does; thus something broke.
> >
> Only if you can prove that 96MB is the proper configuration is this a 
> sign of a bug in 0.20.  An upgrade causing an incorrect configuration to 
> show problems isn't a sign of breakage in 0.20, but a sign of brokenness 
> of previous versions.


In 0.19 mythtv used the default packet buffer size of 1000 firewire 
packets (~4MB) as provided by libeic61883.   The memory used for the 
buffer is kernel space memory instead of user, which is much more limited 
(128M total?).  It was request to allow this buffer size to be  
changeable, so I had just used the HDRingBufferSize size but set a max 
value of 32MB.  

The problem ylee had was when his 2 recorder went to allocate the 32MB of 
kernel memory it was getting denied causing the recording to fail.

I will be setting the max to be 8MB as a temp fix for -fixes tree and plan 
on either making it its own config option or making a 2nd buffer that 
exists in userspace. 


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