[linux-audio-user] I/O scheduler for 2.6 kernel

Mark Knecht markknecht at gmail.com
Fri Sep 30 14:02:17 EDT 2005

On 9/30/05, Antonio <debian at fastwebnet.it> wrote:> On Fri, 2005-09-30 at 12:18 +0200, Carotinho wrote:> [cut]> > I read at> > http://www.jacklab.net/index.php?option=com_content&task=blogcategory&id=236&Itemid=221〈=en_EN> > that you should use the Realtime Preemption Patch and then enable it.> > I'm running a 2.6.12 kernel patched with this and using also the realtime-lsm> > module.> > But now I'm confused, because> > 1) "less /sys/block/hda/queue/scheduler" gives me "noop [anticipatory]> > deadline cfq", so where is the realtime preemption? Is it useful since you do> > not even mention it?>> Maybe you are confusing the Realtime Preemption Patch with the I/O> scheduler. The I/O scheduler do the scheduling for the hd access. While> the Realtime Preemption Patch modifies the processes's scheduler, I> think. They are two different and indipendent things.>> > 2)I discovered that the rlimits way it's better: is it true? Is it also> > simpler than loading the realtime module, which I can do in a straightforward> > way?>> The rlimits is the new (mainline) way to give the user realtime> privileges. The realtime-lsm module wasn't accepted in the mainline> kernel for security risk. So if you don't mind the security risk and you> already know how to compile and load the module, you can continue to use> the realtime-lsm module. At least until your distribution don't include> all the pieces needed to use rlimits. This is my understanding, please> correct me if I'm wrong.>> Best regards,>>   ~ Antonio
Hi,   Yes, I believe these schedulers has different responsibilities.
   Probably I should report this in a separate thread. I do not intendto do any thread hijacking here but it does seem related.
   Yesterday I finally managed to build 2.6.14-rc2-rt7 for my AMD64system. Out of the box it's working very, very well. I've doneabsolutely no configuration of the system. I've not set anythingspecial. Just booted it, started Jack at 128/2 as a user usingrealtime-lsm, and have been streaming ogg files for 4 hours from oneof my 1394a audio drives. In that time I've been browsing the web,doing email and updating the system. I've built a new kernel, copied abunch of files from drive to drive and run a couple of existing Ardoursessions. While all of that was going on I fired up xine and played aDVD movie in the background on my EIDE DVD drive just to create somemore system usage.
   I've not had a single operational xrun in nearly 4 hours. The onlyones I've had come when starting and stopping apps.
   Everything's working great for me, but this is less than 24 hoursso far so take it with a grain of salt.
   This is Gentoo, AMD64 3000+, 512MB, 250GB SATA drive, 4 1394 harddrives( three 1394a and one 1394b) , PCI-Express 16X ATI.
   Note: Executables seem larger on this AMD64 system. I'll needanother 512MB one day soon as I do seee a small amount of swapping onthis system. (<30KB) I never saw that when running 32-bit.

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