linux-kernel - Re: SMP Kernel

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Date:	Sat, 21 Feb 2009 02:07:03 +1100
From:	zaharov <zaharov@...ag.ru>
To:	linux-kernel@...r.kernel.org
Subject: Re: SMP Kernel

Matias wrote:
> Hi,
> Ok, since the memory is shared between all the cores the Kernel can be
> invoked by any core receiving an interrupt and thus executed by that
> core?
>
> If the above is right then how come that two separate CPUs can wake
> up, schedule and context-switch completely in parallel?
> Are there an independent scheduler per cpu?
>
> Directly from the sched-design.txt
>
> - 'perfect' SMP scalability. With the new scheduler there is no 'big'
>   runqueue_lock anymore - it's all per-CPU runqueues and locks - two
>   tasks on two separate CPUs can wake up, schedule and context-switch
>   completely in parallel, without any interlocking. All
>   scheduling-relevant data is structured for maximum scalability.
>
>
> Thx // Matias
>
>
>
>
>
> zaharov skrev:
>> Matias wrote:
>>  
>>> Hello,
>>> When an SMP enabled kernel is booted on a Dual Core x86 machine ( Core
>>> 0-1 ) I guess the Kernel is decompressed and started on core 0.
>>> At some point in time the kernel becomes SMP aware and can then
>>> distribute threads on Cores 0 and 1.
>>>
>>> Now, does the non-threaded part of the kernel with the scheduler
>>> continue to run solely on Core 0?
>>>
>>> Cheers // Matias
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>>>     
>> Kernel may run on any core .
>> When kernel end bootstrap and run init he execute hlt op.
>> After all live in kernel  interrupt driven.
>>
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Kernel use IPC primitives. All shared resources like lists, buffers,etc
protect by spinlock,mutex,etc.
Scheduler not run completely in parallel.
Scheduler  run like this [lock_shred_resource -> shcedule ->
unlock_shared_resource]
I think this list not for discuss this. You need read any Operating
system design book.
IMHO
 
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