On Sunday 17 April 2005 15.44, Hans-Juergen Barthen wrote:
> Hi there !
> I am running svxlink version 050325 on SuSE LinuX 9.0 with kernel
> 2.4.21-280 at DB0LJ-L.
> The PC is a 2.66 GHz machine with 1 GB RAM, a server only, no GUI/no X.
> Nevertheless we get the voice output stuck sometimes.
> The server runs parallel APRS with 30-50 users (javAPRSsrv), a
> packet-radio-BBS, 2 convers-servers, 2 webservers, a forumsoftware based on
> mysql and some other services. There are normally 250-350 processes
> top - 15:24:28 up 17 days, 19:04, 7 users, load average: 13.71, 8.33,
> 7.33 Tasks: 312 total, 39 running, 269 sleeping, 0 stopped, 4 zombie
> Cpu(s): 9.3% user, 28.0% system, 0.0% nice, 62.7% idle
> Mem: 767540k total, 755316k used, 12224k free, 157996k buffers
> Swap: 923696k total, 41892k used, 881804k free, 272676k cached
Quite high load but there seem to be CPU cycles left...
> I found that this is a known problem of audio and video applications, the
> time slices of the OS are getting too small for audio and video
> applications, regardless of CPU-, memory and other resources.
> There are several realtime patches available in the internet to get around
> this problem and the kernel 2.4.21-280 from SuSE, which is running here
> currently, already has realtime features implemented which I don't want to
> overlap with other patches.
> I would like to tune the system for better audio performance but I did not
> find any helpful documentation which value to change how much.
> I only have the few lines of text which come up with "make config" and it
> does not tell very much.
> The realtime parameters of the kernel are:
> CONFIG_MAX_USER_RT_PRIO=100 (max 800)
> The maximum user real-time priority. Tasks with priorities from
> zero through one less than this value are scheduled as real-time.
> To the application, a higher priority value implies a higher
> priority task.
> The minimum allowed value is 100 and the maximum allowed value
> is (arbitrary) 1000. Values specified outside this range will
> be rounded accordingly during compile-time. The default is 100.
> Setting this higher than 100 is safe but will result in slightly
> more processing overhead in the scheduler.
> Unless you are doing specialized real-time computing and require
> a much larger range than usual, the default is fine.
> CONFIG_MAX_RT_PRIO=0 (max 100)
> The difference between the maximum real-time priority and the
> maximum user real-time priority. Usually this value is zero,
> which sets the maximum real-time priority to the same as the
> maximum user real-time priority. Setting this higher,
> however, will allow kernel threads to set their priority to a
> value higher than any user task. This is safe, but will result
> in slightly more processing overhead in the scheduler.
> This value can be at most 200. The default is zero, i.e. the
> maximum priority and maximum user priority are the same.
> Unless you are doing specialized real-time programming with
> kernel threads, the default is fine.
> Maybe the problem is only that I have no experience with this features and
> I am no native english speaker.
> Has anybody any experience with this or other realtime settings to give
> svxlink a better audio performance on machines with higher process load ?
> Or maybe any other patches or settings which work in that case ?
There is a known problem in all released versions of SvxLink. That is
DNS-lookups. DNS-lookups is the only thing that will block SvxLink. This can
cause audio drop-outs since DNS-lookups some times can take several seconds.
Every time the EchoLink registration is updated, the EchoLink directory
server name is looked up (every five minutes or so). Maybe this is your
problem ? Anyway, the DNS problem is solved in CVS so the next release will
not have this problem.
I can think of one workaround for the DNS-problem. Maybe it would help to put
the IP-address/hostname of the EchoLink directory server in the /etc/hosts
file. Try this and tell me if it helps.
73 de SM0SVX / Tobias
> I would not like to run a second server only for this application and as
> far as I understand it is not a problem which can not be fixed.
> By the way:
> I already tried to increase the pci latency value of the audio interface,
> which is default = 0, using:
> DB0LJ:/home/dl5di > setpci -v -s '00:1f.5' latency_timer=80
> 00:1f.5:0d 80
> DB0LJ:/home/dl5di >
> but this does not work at all, the values always stay the same.
> DB0LJ:/home/dl5di > lspci -v -s 00:1f.5
> 00:1f.5 Multimedia audio controller: Intel Corp. 82801DB AC'97 Audio
> Controller (rev 02) Subsystem: Micro-Star International Co., Ltd.: Unknown
> device 7140 Flags: bus master, medium devsel, latency 0, IRQ 9
> I/O ports at c000 [size=256]
> I/O ports at c400 [size=64]
> Memory at e2081000 (32-bit, non-prefetchable) [size=512]
> Memory at e2082000 (32-bit, non-prefetchable) [size=256]
> Capabilities:  Power Management version 2
> The only interface which shows a different value from 0 is the
> ethernetcard, it shows a value of 72.
> Thanks a lot for any helpful advice.
> Best regards
> Hans, DL5DI
> SysOp @DB0LJ, DB0QT, DA5UDI
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