linuxaudio.org

On Mon, Jun 13, 2011 at 05:38:11PM -0700, Fernando Lopez-Lezcano wrote:

quoted text
> Hi all,

>

> I just built a threaded-irqs enabled 2.6.39.1 kernel and used

> cyclictest to try to get an initial feeling of how good it might be.

> Cyclictest tests scheduling delays of the kernel it is running

> on[*]. These tests were run on a Fedora 13 T510 Lenovo laptop, with

> the ugly binary Nvidia driver (caveat emptor).

>

> In the menu:

>

>   2.6.39.1 with threaded irqs and PREEMPT active

>   2.6.33.13-rt31

>   2.6.34.8-rt31 (a forward port of rt31 to 2.6.34)

>   plain Fedora kernel (2.6.34.8-68.fc13.i686.PAE)

>

> Now, before someone points it out, this is just a synthetic test

> that measures scheduling latency, not a real audio application.

still... it provides some numbers.

and what i get seems to differ from what you get pretty heavily.
---( torbenh@siel  )---( ~/cvs/rt-tests )---

-> uname -a

Linux siel 2.6.39 #53 SMP PREEMPT Wed May 25 22:11:00 CEST 2011 x86_64

GNU/Linux

---( torbenh@siel  )---( ~/cvs/rt-tests )---

-> ./cyclictest -t1 -p 80 -n -i 10000 -l 10000 -m

policy: fifo: loadavg: 2.34 1.27 0.54 5/267 10411          
T: 0 ( 7904) P:80 I:10000 C:  10000 Min:      8 Act:   19 Avg:   17 Max:

97

---( torbenh@siel  )---( ~/cvs/rt-tests )---
its just a single run. with a kernel compile in the background.

and thats WITHOUT threadirqs
> See below for details... (look at the "Avg:" and "Max:" latency

quoted text
> values, those are in microseconds)

>

> Unless I have done something wrong, it looks like we have a long way

> to go with regards to scheduling latency in anything other than

> 2.6.33 + rt patches. But, with threaded irqs in 2.6.39 maybe the

> performance with audio applications running under jack will be good

> anyway as we will be able to tune irq processing. Seems to me

> unlikely. I have not tested that yet.

you did not use -m ... although that didnt really change much for me.

but i have plenty of RAM here.
>

quoted text
> Tests were done after a clean reboot, initially with the machine

> idle and then while loading thunderbird with tons of emails and

> firefox with tons of pages. No audio work.

hmm... maybe i should have loaded up ff...

but i loaded midori. because ff was already running.
>

quoted text
> YMMV...

> -- Fernando

>

> [*] https://rt.wiki.kernel.org/index.php/RT_PREEMPT_HOWTO

>

>

> ----------------------------------------------------------------------

> LENOVO T510

> 

--

torben Hohn

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