From: Nick Piggin <piggin@cyberone.com.au>
To: Timothy Miller <miller@techsource.com>
Cc: Con Kolivas <kernel@kolivas.org>,
linux kernel mailing list <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@osdl.org>, Ingo Molnar <mingo@elte.hu>,
gaxt <gaxt@rogers.com>, Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH] O16int for interactivity
Date: Tue, 19 Aug 2003 01:43:54 +1000 [thread overview]
Message-ID: <3F40F43A.4050709@cyberone.com.au> (raw)
In-Reply-To: <3F40F4DA.5050705@techsource.com>
Timothy Miller wrote:
>
>
> Con Kolivas wrote:
>
>>>
>>> A hardware timer interrupt happens at timeslice granularity. If the
>>> interrupt occurs, but the timeslice is not expired, then NORMALLY, the
>>> ISR would just return right back to the running task, but sometimes, it
>>> might decided to end the timeslice early and run some other task.
>>>
>>> Right?
>>
>>
>>
>> No, the timeslice granularity is a hard cut off where a task gets
>> rescheduled and put at the back of the queue again. If there is no
>> other task of equal or better priority it will just start again.
>
>
>
> Hmmm... I'm still having trouble making sense of this.
>
> So, it seems that you're saying that all tasks, regardless of
> timeslice length, are interrupted every 10ms (at 100hz).
Interrupted - in that scheduler_tick is run, yes. They don't get switched.
> If another task exists at a higher priority, then it gets run at
> that point.
Well loosely, yes. Actually, it happens if the task exists and is "running",
and has timeslice left. That only happens in scheduler_tick when the
current
task has finished its timeslice and the priority arrays are about to be
switched. The required conditions for preemption can also occur when a task
is being woken up, (after sleeping or newly forked).
> However, if there is more than one task at a given priority level,
> then they will not round-robin until the current task has used up all
> of its timeslice (some integer multiple of 10ms).
Thats right. Although I think Con or Ingo recently changed this in mm
>
>
> Am I finally correct, or do I still have it wrong? :)
>
Sounds right to me.
next prev parent reply other threads:[~2003-08-18 15:44 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-15 15:49 [PATCH] O16int for interactivity Con Kolivas
2003-08-15 18:26 ` Timothy Miller
2003-08-15 18:45 ` Richard B. Johnson
2003-08-16 2:31 ` Con Kolivas
2003-08-18 15:46 ` Timothy Miller
2003-08-18 15:43 ` Nick Piggin [this message]
2003-08-18 19:48 ` Timothy Miller
2003-08-18 22:46 ` Nick Piggin
2003-08-15 19:00 ` Felipe Alfaro Solana
2003-08-16 2:14 ` [PATCH]O16.1int was " Con Kolivas
2003-08-15 21:01 ` Mike Fedyk
2003-08-15 23:03 ` Scheduler activations (IIRC) question Jamie Lokier
2003-08-15 23:54 ` Mike Fedyk
2003-08-16 0:54 ` Jamie Lokier
2003-08-16 6:14 ` Mike Galbraith
2003-08-16 14:18 ` Jamie Lokier
2003-08-17 5:51 ` Mike Galbraith
2003-08-17 6:55 ` Jamie Lokier
2003-08-17 7:05 ` Nick Piggin
2003-08-17 8:34 ` Mike Galbraith
2003-08-17 17:12 ` Jamie Lokier
2003-08-17 17:15 ` Arjan van de Ven
2003-08-17 18:26 ` Jamie Lokier
2003-08-17 18:27 ` Mike Galbraith
2003-08-17 18:29 ` Jamie Lokier
2003-08-17 18:46 ` Jamie Lokier
2003-08-16 20:54 ` Ingo Oeser
2003-08-16 21:39 ` Jamie Lokier
[not found] ` <20030817144203.J670@nightmaster.csn.tu-chemnitz.de>
2003-08-17 20:02 ` Jamie Lokier
2003-08-18 0:23 ` William Lee Irwin III
2003-08-18 10:38 ` Ingo Oeser
2003-08-18 13:09 ` Jamie Lokier
2003-08-16 7:01 ` [PATCH] O16int for interactivity Con Kolivas
2003-08-18 10:08 ` Apurva Mehta
2003-08-18 10:30 ` Con Kolivas
2003-08-18 12:13 ` Apurva Mehta
2003-08-15 20:50 Voluspa
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