[LAU] resubmitting questions from last week

Paul Neaveill boycotthell2005 at yahoo.com
Tue Aug 4 18:50:24 EDT 2009

Thanks to my neighbor a few hours north, Brent for the confirmation.  Was not aware of any "quota" on questions and did not mean to monopolize anything, just trying to learn some things here. Apologies if error was made.

Thanks to Brent's assist, am now aware that those are IRQ statements, but still uncertain where to plug those in. Guess will keep googling in search of answers.

--- On Tue, 8/4/09, Brent Busby <brent at keycorner.org> wrote:

From: Brent Busby <brent at keycorner.org>
Subject: Re: [LAU] resubmitting questions from last week
To: "Linux Audio User" <linux-audio-user at lists.linuxaudio.org>, "Paul Neaveill" <boycotthell2005 at yahoo.com>
Date: Tuesday, August 4, 2009, 1:35 PM

On Mon, 3 Aug 2009, Paul Neaveill wrote:

> Sorry if someone responded and we missed it, but despite much googling and all of that, am still working on getting my own kernel(s) [2 machines] going with the following as had been suggested last week:
> preempt_RCU
> No_Hz
> HZ_1000
> and the other Rock-solid low-latency audio tweaks
> 99 ff migration
> 99 ff posixcputmr
> 98 ff IRQ-8 (real-time clock)
> 97 ff audio IRQ
> 80 rr Jack
> Found the preempt_RCU and HZ_1000 spots in the debian/ubuntu kernel hack, still looking for the rest please.?
> ** Would really appreciate the assistance with figuring out where/how to put those.

I never did get an answer to some of those questions either, so I figured maybe I'd been asking too many.  (I have been posting a lot of them lately.)

I think the ones you've got at the top for kernel options should be safe.  I'm going to try -- at least initially -- not adjusting any IRQ priorities though.  It might work, considering I've got a fast machine, and from what I hear, there are even people getting away with ordinary non-RT kernels these days.

Preempt RCU was supposed to be buggy for awhile, but tested now for two years...  (Source:  LKML)

Somebody said NO_HZ was actually a good thing on a laptop being used for pro-audio, and I suppose if you can do well on a laptop you can do well anywhere...  (Source:  Some guy with a laptop.)

And HZ_1000 is recommended almost everywhere.

I don't know what the meaning of NO_HZ and HZ_1000 is together, but I guess it'd mean a jiffy rate of 1000Hz, but only when interrupts are needed?

I'm just putting stuff together from lots of googling too...

-- + Brent A. Busby     + "We've all heard that a million monkeys
+ UNIX Systems Admin     +  banging on a million typewriters will
+ University of Chicago     +  eventually reproduce the entire works of
+ Physical Sciences Div. +  Shakespeare.  Now, thanks to the Internet,
+ James Franck Institute +  we know this is not true." -Robert Wilensky

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