Message-ID: <41F42BD2.4000709@kolivas.org>
Date: Mon, 24 Jan 2005 09:57:22 +1100
From: Con Kolivas <kernel@kolivas.org>
User-Agent: Mozilla Thunderbird 1.0 (X11/20041206)
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To: "Jack O'Quin" <joq@io.com>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Davis <paul@linuxaudiosystems.com>,
       linux <linux-kernel@vger.kernel.org>, rlrevell@joe-job.com,
       CK Kernel <ck@vds.kolivas.org>, utz <utz@s2y4n2c.de>,
       Andrew Morton <akpm@osdl.org>, alexn@dsv.su.se,
       Rui Nuno Capela <rncbc@rncbc.org>
Subject: Re: [PATCH]sched: Isochronous class v2 for unprivileged soft rt scheduling
References: <200501201542.j0KFgOwo019109@localhost.localdomain>	<87y8eo9hed.fsf@sulphur.joq.us> <20050120172506.GA20295@elte.hu>	<87wtu6fho8.fsf@sulphur.joq.us> <20050122165458.GA14426@elte.hu> <87pszvlvma.fsf@sulphur.joq.us>
In-Reply-To: <87pszvlvma.fsf@sulphur.joq.us>
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Jack O'Quin wrote:
> Looked at this way, there really is no question.  The new scheduler
> prototypes are falling short significantly.  Could this be due to
> their lack of priority distinctions between realtime threads?  Maybe.
> I can't say for sure.  I'll be interested to see what happens when Con
> is ready for me to try his new priority-based SCHED_ISO prototype.

There are two things that the SCHED_ISO you tried is not that SCHED_FIFO 
is - As you mentioned there is no priority support, and it is RR, not 
FIFO. I am not sure whether it is one and or the other responsible. Both 
can be added to SCHED_ISO. I haven't looked at jackd code but it should 
be trivial to change SCHED_FIFO to SCHED_RR to see if RR with priority 
support is enough or not. Second the patch I sent you is fine for 
testing; I was hoping you would try it. What you can't do with it is 
spawn lots of userspace apps safely SCHED_ISO with it - it will crash, 
but it not take down your hard disk. I've had significantly better 
results with that patch so far. Then we cn take it from there.

Cheers,
Con

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