linux-kernel - Re: BFS 420: cleanup in tick handling

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Message-ID: <CAJd=RBArne+LupLRxiCUAyCV16Xg4VVLn6R=uU2QPPJk_cdS0w@mail.gmail.com>
Date:	Tue, 22 May 2012 22:09:36 +0800
From:	Hillf Danton <dhillf@...il.com>
To:	Chen <hi3766691@...il.com>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: BFS 420: cleanup in tick handling

On Tue, May 22, 2012 at 10:07 PM, Chen <hi3766691@...il.com> wrote:
>
> 在 2012-5-22 下午10:04，"Hillf Danton" <dhillf@...il.com>写道：
>
>
>>
>> On Tue, May 22, 2012 at 10:00 PM, Chen <hi3766691@...il.com> wrote:
>> >
>> > 在 2012-5-22 下午9:50，"Hillf Danton" <dhillf@...il.com>写道：
>> >>
>> >> On Tue, May 22, 2012 at 9:45 PM, Chen <hi3766691@...il.com> wrote:
>> >> > Actually the lowest deadline task selection algorithm now BFS used is
>> >> > O(n).
>> >> > I have already had an idea to enhance the lowest deadline task
>> >> > selection
>> >> > algorithm to O(1)
>> >>
>> >> Would you please announce it on LKML?
>> >
>> > First of all let me talk how to do it .We can use 40 list_head instead
>> > of
>> > the single list for time sharing scheduling policy.
>> > Then for task selection we will select the task from these 40
>> > list_head(actually not 40, just decide by next_sched_bit), then make a
>> > comparsion of these tasks(actually in the worse case we just need to do
>> > 40
>> > times of comparsion) and pick the lowest task. If a task wake, it would
>> > be
>> > the first node of (queue + p->prio). If a task run out of its timeslice,
>> > it
>> > will become the last node of(queue + p->prio). This is a concept of BFS
>> > deadline presort algorithm and the time complexity is O(1)
>>
>> Thank you for shedding light, I will study it soon.
> If you are free could you also help me to maintain my cpu scheduler, thanks.
> . :-)
No promise but try my best, ok?
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