Date: Tue, 16 Nov 2010 20:56:50 -0500
From: Kyle McMartin <kyle@mcmartin.ca>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>, Mike Galbraith <efault@gmx.de>,
        Oleg Nesterov <oleg@redhat.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Markus Trippelsdorf <markus@trippelsdorf.de>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC/RFT PATCH v3] sched: automated per tty task groups
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On Tue, Nov 16, 2010 at 05:50:41PM -0800, Linus Torvalds wrote:
> Blame me, I threw that out as a single point where this can be done.
> 
> In fact, holding the signal spinlock was seen as a bonus, since that
> was used to serialize the access to the signal->autogroup access.
> Which I think is required.
> 
> But yes, it does create problems for the allocation. It could be done
> as just a GFP_ATOMIC, of course, and on allocation failure you'd just
> punt and not do it. Not pretty, but functional.
> 

Yeah, I didn't look any deeper than kernel/sched.c::sched_create_group,
but that would need to GFP_ATOMIC as well.

Looking at it now, so would alloc_rt_sched_group/alloc_fair_sched_group,
and we're looking at an awful lot of sleepless allocations. Not sure
that's a feasible plan.

--Kyle
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