[SATLUG] simultaneously burning multiple DVDs

Kevin Buckner sirjaggy29 at gmail.com
Wed Dec 31 10:27:59 CST 2014

Software does not always take advantage of the capabilities of hardware.
Just because the system has enough RAM doesn't equate the peripherals
software is taking advantage of it. The system bus also is not a factor in
it because again the device driver software for either the DVD controller
or DVD authoring software may not be on par with hardware. A device
controller on the hardware maybe able to daisy chain several devices but
the driver software may access in a sequential read write.  Otherwise the
driver software may not be up to par in reading writing to several devices.
On Dec 31, 2014 8:13 AM, "Borries Demeler" <demeler at biochem.uthscsa.edu>

This machine has 32 GB RAM with a 5 GB dedicated RAM drive. No swap
is set up, so it won't happen.
There should be more than enough RAM to run the system without swapping.
Again, I cannot fathom that the limitation is in reading the source file.


On Wed, Dec 31, 2014 at 02:02:15AM -0600, Craig wrote:
> *Borries Demeler* on  *Tue Dec 30 11:35:29 CST 2014 *wrote:
> >  If I needed 2 MB on board memory buffer, does that ninux cannot supply
> > the data fast enough to the drive if I use more than one drive?
> >
> > If so, the question comes up why Linux cannot do that. Assuming I use a
> RAM drive
> > as the source for the iso to be written to multiple drives, is it
> the
> > RAM drive is too slow to be read?? That I find hard to believe.
> > So is it because the data cannot be moved fast enough through the system
> bus?
> > With Gbit bus speeds, I also find this hard to believe.
> > Is it because the CPU is too slow? I have multiple cores, each could run
> > a separate process, so this can't possibly be the reason either.
> >
> > I am still stumped why this doesn't work as expected.
> Are you absolutely sure the ram drive is non-swappable?
> If the ram drive or portion there of gets sent to disk swap (e.g. the
> portion not yet burned,
> but not in use), then needs to be swapped back in from disk (or portions
> there of) when it's time
> to be used, actual physical ram read access might not happen in time for
> the buffer to be sent data
> in time to  prevent buffer underrun.
> -- particularly if swap is on a platter drive and/or other things are
> jockying for use of the remaining
> hard ram (e.g. swapped between swap space & physical ram).  Obviously in
> this case, DVD data transfer
> will be slower/lower priority than swapping between physical ram / virtual
> ram.
> Even if the ram drive is marked as "do not swap out of physical ram",
> without a real time kernel,
> swapping programs between physical ram & swap space can easily create
> enough timing issues
> which would destroy any advantages gained by the non-swappable ram drive.
> So, having a ram drive may actually make things worse.
> A non-real time kernel does not guarantee availability of resources at a
> fixed point in time.
> ** try opening multiple tabs under a web browser, where each tab has a
> youtube or flash media link.
>     How many does it take before the active tab video starts skipping?
> (take a look at vmstat / available memory & swap usage)
>     How many tabs does it take before it becomes a chore to switch between
> tabs? (take a look at iostat e.g. swap usage! ).
>     How many open/active tabs before the web browser crashes under the
> strain?
> --
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