Date: Sun, 11 Nov 2007 12:25:51 +0200 From: Alexander Motin <mav@FreeBSD.org> Cc: freebsd-arch@freebsd.org Subject: Re: Kernel thread stack usage Message-ID: <4736D8AF.7010209@FreeBSD.org> In-Reply-To: <1191189248.00807488.1191177603@10.7.7.3> References: <1191187393.00807485.1191175801@10.7.7.3> <1191189248.00807488.1191177603@10.7.7.3>
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> 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?
Digging kernel with a dirty hands I have found the way which looks like
working. I have briefly tested it on i386.
printf("%p, %p. Used %d of %d.\n", &var,
(char *)td->td_kstack + td->td_kstack_pages * PAGE_SIZE,
(char *)td->td_kstack + td->td_kstack_pages * PAGE_SIZE -
(char *)&var,
td->td_kstack_pages * PAGE_SIZE);
'var' here is a name of some local variable.
Can anybody comment correctness of this way or propose another one?
--
Alexander Motin
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