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Date:      Sun, 30 Sep 2007 20:32:27 +0200
From:      "Attilio Rao" <attilio@freebsd.org>
To:        "Alexander Motin" <mav@freebsd.org>
Cc:        freebsd-arch@freebsd.org
Subject:   Re: Kernel thread stack usage
Message-ID:  <3bbf2fe10709301132j441277e1web97323743d01560@mail.gmail.com>
In-Reply-To: <46FFD850.1040508@FreeBSD.org>
References:  <46FFD850.1040508@FreeBSD.org>

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2007/9/30, Alexander Motin <mav@freebsd.org>:
> Hi.
>
> As known in netgraph susbystem information passing from one node to
> another by direct function calls without queueing. It gives performance
> bonuses, but it also gives permanent stack overflow risk on complicated
> graphs. Netgraph is still have a queues and able to use them when asked,
> but now queueing is a flag which should be controlled by sending node. I
> think it would be good to implement some algorithm which could monitor
> stack usage on each call and enforce queueing when stack usage become
> critical.
>
> The question is: is there correct way to somehow get current kernel
> thread stack usage or just a stack base address?

This should be stored in the pcb area of threads (for example, ia32
maintains a pcb_esp0 which points to the stack address at ring0 for
the thread which points to).

Attilio


-- 
Peace can only be achieved by understanding - A. Einstein



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