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To: Ingo Molnar <mingo@elte.hu>
cc: Con Kolivas <kernel@kolivas.org>, "Bill Huey (hui)" <bhuey@lnxw.com>,
       "Jack O'Quin" <joq@io.com>, Nick Piggin <nickpiggin@yahoo.com.au>,
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       Rui Nuno Capela <rncbc@rncbc.org>, Chris Wright <chrisw@osdl.org>,
       Arjan van de Ven <arjanv@redhat.com>
Subject: Re: [patch, 2.6.11-rc2] sched: RLIMIT_RT_CPU_RATIO feature 
In-reply-to: Your message of "Thu, 03 Feb 2005 22:59:27 +0100."
             <20050203215927.GA28634@elte.hu> 
Date: Thu, 03 Feb 2005 17:24:14 -0500
From: Paul Davis <paul@linuxaudiosystems.com>
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>that might be all well and good, but i believe you still dont understand
>my point: for yield_to() to work the target task _needs to be running_. 

correct, i did not understand. perhaps Con didn't either. my idea was
related to:

>in theory it would be possible to add two new syscalls: sys_suspend()
>and sys_wakeup(tid), where suspend would just enter TASK_INTERRUPTIBLE

but more like:

    sys_suspend_and_wake (tid)

where current enters TASK_INTERRUPTIBLE, and process_wakeup() is
called on tid.

>having this API on 2.4 kernels. But it would have one big advantage: it
>would be evidently and trivially RT-safe :-)

no small advantage.

it has another big advantage from the user space perspective: no other
information is required apart from <tid>. no state needs to be
maintained by the system that uses this. thats a huge win over the
baroque collection of FIFOs (or futexes) that we have to look after now.

--p
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