Mailing List Archive

Has anybody put together a three tuner system ?
Is this even possible. I have an XP2400 athlon and wonder if this is
powerful enough for this setup. I recently was able to free 2 pci
slots.
Re: Has anybody put together a three tuner system ? [ In reply to ]
cmisip wrote:
> Is this even possible. I have an XP2400 athlon and wonder if this is
> powerful enough for this setup. I recently was able to free 2 pci
> slots.

I did run a system with three cards once just to verify
that the scheduler would work correctly. I would not
recommend more than two cards per machine simply because
there is so much resource contention (not just CPU). Two
'cheap' machines with two tuners each will give you better
recordings than a tricked out machine to try to handle
three. The problem is that you have to set your recording
parameters low enough that it can handle three if it ever
happens. Most of the time, you'd have a very expensive
machine that is mostly dormant putting out low res files.

-- bjm
Re: Has anybody put together a three tuner system ? [ In reply to ]
Yes, I have 2xWinTV 401 and a PVR250 running
on a dual P2-450. There are some minor problems,
but I'm running a month old CVS version. Nothing
too major.

As for the power of your 2400, really depends on
how jacked up you want the resolution and quality
numbers. My 450's don't have the power to encode
at a high quality number, but the dual cpus really
help with the multiple tuners. If I'm willing
to accept a few jumps, I can record 3 and play 1
at the same time.

I've considered specing out a new machine and
from the info I've heard reported, I would guess
your 2400 would have problems with 3 cards set
at high quality numbers. Once multiple PVRs
get stable, probably have less trouble, but
you may run into HD limitations. I have 3 SCSI
80MB drives in a raid.

Brian


On Saturday 31 May 2003 11:13 am, cmisip wrote:
> Is this even possible. I have an XP2400 athlon and wonder if this is
> powerful enough for this setup. I recently was able to free 2 pci
> slots.
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
RE: Has anybody put together a three tuner system ? [ In reply to ]
I agree here with Bruce. Two machines is better for ease of use but
obviously there is the power consumption issues to consider.

My XP2000+ takes around 50% encoding a 640x576 MPEG4 stream (default MythTV
settings) and around 5-10% decoding. Obviously a 2400 won't help heaps in
terms of 3 cards. IDE bandwidth issues etc start to become an issue too.

If you're willing to go down to say 480x576 (about 33% each on my CPU) you
might squeeze it in. Having some headroom (10-15%) is better if something
else happens on the box though.

Perhaps 2 PVR250 cards might be alright in terms of CPU but disregarding
IDE/PCI bandwidth etc.

I'd be interested to see how you go though. Care to be the guinea pig? ;)

CH

> -----Original Message-----
> From: mythtv-users-bounces@snowman.net
> [mailto:mythtv-users-bounces@snowman.net]On Behalf Of Bruce Markey
> Sent: Monday, 2 June 2003 6:14 AM
> To: Discussion about mythtv
> Subject: Re: [mythtv-users] Has anybody put together a three tuner
> system ?
>
>
> cmisip wrote:
> > Is this even possible. I have an XP2400 athlon and wonder if this is
> > powerful enough for this setup. I recently was able to free 2 pci
> > slots.
>
> I did run a system with three cards once just to verify
> that the scheduler would work correctly. I would not
> recommend more than two cards per machine simply because
> there is so much resource contention (not just CPU). Two
> 'cheap' machines with two tuners each will give you better
> recordings than a tricked out machine to try to handle
> three. The problem is that you have to set your recording
> parameters low enough that it can handle three if it ever
> happens. Most of the time, you'd have a very expensive
> machine that is mostly dormant putting out low res files.
>
> -- bjm
>
>
Re: Has anybody put together a three tuner system ? [ In reply to ]
I did not even think about the ide hd problems I might run into. I
might be able to pick up a wintv go for cheap because of msn dollars. I
think I will give it a try. If it doesnt work I can always put it in
the other frontend in the kitchen ( a PIII 1 Ghz ) and make that a
backend also. I have some questions though. In a multiple backend
system, If one slave backend is offline, does the recording get
transferred to the main backend. I dont intend to keep both machines up
and running all the time if I do put together another backend. And is
the wintv go pci tv card ok ? Does it work with btaudio? Thanks



On Sun, 2003-06-01 at 23:41, Brian Foddy wrote:
> Yes, I have 2xWinTV 401 and a PVR250 running
> on a dual P2-450. There are some minor problems,
> but I'm running a month old CVS version. Nothing
> too major.
>
> As for the power of your 2400, really depends on
> how jacked up you want the resolution and quality
> numbers. My 450's don't have the power to encode
> at a high quality number, but the dual cpus really
> help with the multiple tuners. If I'm willing
> to accept a few jumps, I can record 3 and play 1
> at the same time.
>
> I've considered specing out a new machine and
> from the info I've heard reported, I would guess
> your 2400 would have problems with 3 cards set
> at high quality numbers. Once multiple PVRs
> get stable, probably have less trouble, but
> you may run into HD limitations. I have 3 SCSI
> 80MB drives in a raid.
>
> Brian
>
>
> On Saturday 31 May 2003 11:13 am, cmisip wrote:
> > Is this even possible. I have an XP2400 athlon and wonder if this is
> > powerful enough for this setup. I recently was able to free 2 pci
> > slots.
> >
> > _______________________________________________
> > mythtv-users mailing list
> > mythtv-users@snowman.net
> > http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
Re: Has anybody put together a three tuner system ? [ In reply to ]
cmisip wrote:
> I did not even think about the ide hd problems I might run into. I
> might be able to pick up a wintv go for cheap because of msn dollars. I
> think I will give it a try. If it doesnt work I can always put it in
> the other frontend in the kitchen ( a PIII 1 Ghz ) and make that a
> backend also. I have some questions though. In a multiple backend
> system, If one slave backend is offline, does the recording get
> transferred to the main backend. I dont intend to keep both machines up
> and running all the time if I do put together another backend.

Yes it does. Good question. Each time the scheduler runs
it checks to see which cards are available then assigns the
recordings to the available cards (actually, card inputs
for the sourceid). So you can startup and shutdown slaves
and the scheduler will do the right thing. I do this
intentionally. Robert and I talked about this and other
multi-backend trickery then he wrote this:

http://www.mythtv.org/docs/mythtv-HOWTO-19.html#ss19.13

One of the drawbacks in my setup is that I use local disks
so I can only watch recordings from a slave when that slave
is up. Robert solves this by using NFS and added a feature
so that the master backend can use recordings on the NFS
partition even when the slave that recorded it is not up.

-- bjm
Re: Has anybody put together a three tuner system ? [ In reply to ]
My current master (and only backend) has its /mnt/store partition
exported via nfs. I thought it was necessary until I found out that
mythfrontend from another machine could access the videos on the master
backend system without the nfs partition being exported. You're saying
then that If I want the recordings available all the time even if the
slaves are not running, I need to maintain this setup and have the slave
write to the master's exported nfs partition? I have another question,
is there an on screen warning that notifies me that the slave backend is
recording If I decide to exit and shutdown? Or do I always need to
check the Watch a REcording screen to determine if the slave backend is
busy ( by counting the number of currently recording programs and
knowing which encoder is associated to each recording). If this is not
the case, it would be neat to have this feature. It would even be
better if upon selecting exit and shutdown it automatically shutdowns at
the conclusion of the current recording and the master automatically
knows not to assign the next recording to this slave. I am leaning more
and more towards a multibackend system. I think my PIII 1 Ghz is good
for at least 1 TV card. Thanks


On Mon, 2003-06-02 at 17:55, Bruce Markey wrote:
> cmisip wrote:
> > I did not even think about the ide hd problems I might run into. I
> > might be able to pick up a wintv go for cheap because of msn dollars. I
> > think I will give it a try. If it doesnt work I can always put it in
> > the other frontend in the kitchen ( a PIII 1 Ghz ) and make that a
> > backend also. I have some questions though. In a multiple backend
> > system, If one slave backend is offline, does the recording get
> > transferred to the main backend. I dont intend to keep both machines up
> > and running all the time if I do put together another backend.
>
> Yes it does. Good question. Each time the scheduler runs
> it checks to see which cards are available then assigns the
> recordings to the available cards (actually, card inputs
> for the sourceid). So you can startup and shutdown slaves
> and the scheduler will do the right thing. I do this
> intentionally. Robert and I talked about this and other
> multi-backend trickery then he wrote this:
>
> http://www.mythtv.org/docs/mythtv-HOWTO-19.html#ss19.13
>
> One of the drawbacks in my setup is that I use local disks
> so I can only watch recordings from a slave when that slave
> is up. Robert solves this by using NFS and added a feature
> so that the master backend can use recordings on the NFS
> partition even when the slave that recorded it is not up.
>
> -- bjm
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
Re: Has anybody put together a three tuner system ? [ In reply to ]
cmisip wrote:
> My current master (and only backend) has its /mnt/store partition
> exported via nfs. I thought it was necessary until I found out that
> mythfrontend from another machine could access the videos on the master
> backend system without the nfs partition being exported.

Correct.

> ... You're saying
> then that If I want the recordings available all the time even if the
> slaves are not running, I need to maintain this setup and have the slave
> write to the master's exported nfs partition?

If a slave writes to a directory that is not shared with the
master and the slave backend process is not running, the
frontend cannot play the files from the slave. Robert's feature
allows the master to treat any file it finds in the master
backend dir as being it's own even if the 'recorded' table says
it belong to a slave. Therefore, you can record from the slave
to the NFS partition then later watch the recording even if the
slave is not running.

If you use a local disk on the slave, you simply need to run
the backend when you want to watch those recordings.

> I have another question,
> is there an on screen warning that notifies me that the slave backend is
> recording If I decide to exit and shutdown?

Realize that this is the backend and not the frontend so when
it comes time to shutdown the backend, you are at the command
line and not the GUI. I look at top or ps to make sure there
isn't a backend using CPU. When the slave 'has left the building'
(very funny, Isaac), the schedule would be recalculated.

-- bjm
Re: Has anybody put together a three tuner system ? [ In reply to ]
What I meant was when I select "Yes and shutdown the computer" from the
mythfrontend gui (on the nommaster backend machines) , it would be nice
if it would check to make sure the local backend is not busy recording a
show before executing the shutdown command. If the local backend is
busy, maybe let the frontend announce to the master that it is no longer
taking any orders and execute the shutdown command after a delay greater
than the remaining time to finnish the current recording or something
like that. Some kind of countdown timer might be displayed and If the
user decides to cancel the shutdown and continue watching, the process
can be reversed.



> > I have another question,
> > is there an on screen warning that notifies me that the slave backend is
> > recording If I decide to exit and shutdown?
>
> Realize that this is the backend and not the frontend so when
> it comes time to shutdown the backend, you are at the command
> line and not the GUI. I look at top or ps to make sure there
> isn't a backend using CPU. When the slave 'has left the building'
> (very funny, Isaac), the schedule would be recalculated.
>
> -- bjm
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
Re: Has anybody put together a three tuner system [ In reply to ]
Just as a data point, I'm running MythTV 0.9 (yeah I just
downloaded it!) on RedHat 9 with an AMD XP 2200+. My hard drive
returns about 53MB/s from hdparm. Even when tuned down to 320x240
resolution with RTJpeg, I get skipping while trying to record 3
programs and watching one of the recordings. The hard drive is
getting pretty beat up, so without actually making a careful analysis
with iostat/sar I think the problem my be device contention.

With these I get the following:

1) Recording two programs: 40% idle CPU
2) Recording two program+LiveTv 30% idle CPU (sometimes <10%)
3) Recording three programs <10% idle CPU
4) Recording three programs+watch one 0% idle CPU

When I reviewed one of the recordings from #3 above, it had some
occassional skipping. When trying to run in type #4, the skipping is
sometimes really bad, other times it is acceptable. It's kinda strange.
I'm not clear on why there is such a discrepancy between #2 and #3 - it
seems like LiveTV should be about the same amount of work as recording
three programs? I would probably get more consisten results from sar
(oh, I did make sure that stuff like updatedb was not running, cause
that one really hurts)

In any event, with such little overhead to spare, common tasks like
channel changing and skipping forward crawl along (compared to normal). I
probably won't actually run this system with three cards (I just happened to
have three and thought I would try it. Actually, I have four cards, but I'm
obviously not going to bother with that many :)

-poul
RE: Has anybody put together a three tuner system [ In reply to ]
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The only possible three or more tuner combination I can think of
that's even in the realm of "reasonable" is going to involve at least
one (or more) PVR-250 cards, just to cut down on the PCI bandwidth
issues. Getting super fancy with multiple PCI busses, or a 64bit PCI
bus and cards (not that I believe that you can get a 64bit capture
card cheaply) and fast processors is going to end up costing more
than just getting two or more cheaper boxes.

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RE: Has anybody put together a three tuner system [ In reply to ]
On my dual P2-450,
Certainly its a tough stretch. I run 3 tuners (2 401's and a PVR250)
but I don't have the CPU to do everything and watch a 4th show
without significant skips. Recording 3 with no watching
however is suprisingly useable. I use 640x240
resolution with rtjpeg @200 settings. I don't encode audio, and I can't
deinterlace at all on a P2 machine. I have 3 HDs in the system (2 80MB
SCSI and an IDE, all 3 in an Linear Raid config, most of the space is
on 1 18GB 10k drive).

In summary tho, by adding a 2nd cpu to a system you go a long
way towards it. I haven't tried putting all this in a
dual P3-1000 machine I also have, its doing other work. But
the added CPU power may make a lot of difference.

Question: Any thoughts on how I can see if its PCI bandwidth,
HD limits, or CPU? When my machine starts skipping bad, the
CPU load actually goes down. Is that because the frame buffers
are full and and new ones are skipped, or possibly PCI or HD
limitations. The answer may influence how I upgrade my system
to a permanent solution.


Brian


On Tue, 10 Jun 2003, Robert Kulagowski wrote:

>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> The only possible three or more tuner combination I can think of
> that's even in the realm of "reasonable" is going to involve at least
> one (or more) PVR-250 cards, just to cut down on the PCI bandwidth
> issues. Getting super fancy with multiple PCI busses, or a 64bit PCI
> bus and cards (not that I believe that you can get a 64bit capture
> card cheaply) and fast processors is going to end up costing more
> than just getting two or more cheaper boxes.
>
> -----BEGIN PGP SIGNATURE-----
> Version: PGPfreeware 7.0.3 for non-commercial use <http://www.pgp.com>
>
> iQA/AwUBPuXmgPc1NpCTlP0JEQJtsQCfSHIY7YxmpgqE/8Pic1D5Ub6OaZUAn030
> jNsp4p7GrL2x1BTKZURqV3R/
> =IOok
> -----END PGP SIGNATURE-----
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
>
>
RE: Has anybody put together a three tuner system [ In reply to ]
On Tue, 2003-06-10 at 14:44, Brian Foddy wrote:
> On my dual P2-450,
> Certainly its a tough stretch. I run 3 tuners (2 401's and a PVR250)
> but I don't have the CPU to do everything and watch a 4th show
> without significant skips. Recording 3 with no watching
> however is suprisingly useable. I use 640x240
> resolution with rtjpeg @200 settings. I don't encode audio, and I can't
> deinterlace at all on a P2 machine. I have 3 HDs in the system (2 80MB
> SCSI and an IDE, all 3 in an Linear Raid config, most of the space is
> on 1 18GB 10k drive).
>
> In summary tho, by adding a 2nd cpu to a system you go a long
> way towards it. I haven't tried putting all this in a
> dual P3-1000 machine I also have, its doing other work. But
> the added CPU power may make a lot of difference.
>
> Question: Any thoughts on how I can see if its PCI bandwidth,
> HD limits, or CPU? When my machine starts skipping bad, the
> CPU load actually goes down. Is that because the frame buffers
> are full and and new ones are skipped, or possibly PCI or HD
> limitations. The answer may influence how I upgrade my system
> to a permanent solution.

Have you tryed doing a 'tail -f /var/log/syslog' or 'tail -f
/var/log/messages' to see if there are any errors when this occurs?

Jayson Garrell
Re: Has anybody put together a three tuner system [ In reply to ]
> Question: Any thoughts on how I can see if its PCI bandwidth,
> HD limits, or CPU? When my machine starts skipping bad, the
> CPU load actually goes down. Is that because the frame buffers
> are full and and new ones are skipped, or possibly PCI or HD
> limitations. The answer may influence how I upgrade my system
> to a permanent solution.

That might make sense - if the disk gets behind and the encoder
decides to drop a frame or two to catch up, then that would would
temporarily reduce the work the CPU has to do. If you want to get a good
idea of where the bottlenecks are in your system, have a look at systat
(http://perso.wanadoo.fr/sebastien.godard/) It has many features and
capabilities especially on Linux; too many to go into here. Basically
you can configure the "sa1" command to log performance statistics at a
regular interval and then use the "sar" command to extract the
interesting bits. Then follow basic analysis technique: establish a
baseline with a quiscient system, etc...

-poul
Re: Has anybody put together a three tuner system [ In reply to ]
The only messages I see in /var/log/messages and syslog
of any warning type is are from ivtv like:
Jun 9 18:00:01 cyclone kernel: ivtv: Not enough free buffers, stream 0
Jun 9 18:00:10 cyclone last message repeated 289 times

So obviously, I'm pushing something too hard,
just not sure what yet.

Brian


On Tuesday 10 June 2003 05:04 pm, Jayson Garrell wrote:
> On Tue, 2003-06-10 at 14:44, Brian Foddy wrote:
> > On my dual P2-450,
> > Certainly its a tough stretch. I run 3 tuners (2 401's and a PVR250)
> > but I don't have the CPU to do everything and watch a 4th show
> > without significant skips. Recording 3 with no watching
> > however is suprisingly useable. I use 640x240
> > resolution with rtjpeg @200 settings. I don't encode audio, and I can't
> > deinterlace at all on a P2 machine. I have 3 HDs in the system (2 80MB
> > SCSI and an IDE, all 3 in an Linear Raid config, most of the space is
> > on 1 18GB 10k drive).
> >
> > In summary tho, by adding a 2nd cpu to a system you go a long
> > way towards it. I haven't tried putting all this in a
> > dual P3-1000 machine I also have, its doing other work. But
> > the added CPU power may make a lot of difference.
> >
> > Question: Any thoughts on how I can see if its PCI bandwidth,
> > HD limits, or CPU? When my machine starts skipping bad, the
> > CPU load actually goes down. Is that because the frame buffers
> > are full and and new ones are skipped, or possibly PCI or HD
> > limitations. The answer may influence how I upgrade my system
> > to a permanent solution.
>
> Have you tryed doing a 'tail -f /var/log/syslog' or 'tail -f
> /var/log/messages' to see if there are any errors when this occurs?
>
> Jayson Garrell
>
>
> _______________________________________________
> mythtv-users mailing list
> mythtv-users@snowman.net
> http://lists.snowman.net/cgi-bin/mailman/listinfo/mythtv-users
RE: Has anybody put together a three tuner system [ In reply to ]
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

> The only messages I see in /var/log/messages and syslog
> of any warning type is are from ivtv like:
> Jun 9 18:00:01 cyclone kernel: ivtv: Not enough free
> buffers, stream 0
> Jun 9 18:00:10 cyclone last message repeated 289 times

You're pushing everything too hard; the system can't pull the data
off the card fast enough.

[root@livingroom mythtv]# modinfo-24 ivtv
filename:
/lib/modules/2.4.21-0.1mdk/kernel/drivers/media/video/ivtv.o
description: "Alpha iTVC15 driver"
author: "Kevin Thayer"
license: "GPL"
parm: yuv_fixup int, description "
Toggles conversion of Hauppauge Macroblock NV12 to NV12
"
parm: yuv_buffers int, description "
Number of 32K buffers for copying YUV. Default: 60, Min: 40
"
parm: mpg_buffers int, description "
Number of 32K buffers for copying mpg. Default: 30, Min.: 10
"
parm: num_devices int, description "
Number of supported devices (1-9). Default: 1
"
parm: debug int, description "
Debug level (bitmask), default, errors only
(debug=127 gives full debuging)
"

# cat /etc/modules.conf
options ivtv mpg_buffers=99

See if that helps, but I think you've got a Lucy in the Chocolate
Factory on your hands.

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