From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: paulmck@linux.vnet.ibm.com, Steven Rostedt <rostedt@goodmis.org>,
linux-kernel@vger.kernel.org, tony@bakeyournoodle.com,
paulus@samba.org, dino@in.ibm.com, tytso@us.ibm.com,
dvhltc@us.ibm.com, niv@us.ibm.com, antonb@us.ibm.com,
Ingo Molnar <mingo@elte.hu>
Subject: Re: [PATCH, RFC] improved hacks to allow -rt to run kernbench on POWER
Date: Tue, 13 Nov 2007 20:43:46 +1100 [thread overview]
Message-ID: <1194947026.18185.95.camel@pasglop> (raw)
In-Reply-To: <1194945032.6983.11.camel@twins>
On Tue, 2007-11-13 at 10:10 +0100, Peter Zijlstra wrote:
>
> Correct, -rt can't allocate -anything- when preemption if off. That is
> the cost for having the allocators itself preemptable.
>
> Even radix_tree_preload() will not work as its functionality was based
> on preempt disable to limit access to a global (per cpu) object
> reserve.
> But maybe something similar could be done with a local reserve by
> using
> struct radix_tree_context to pass it along.
>
> I'll see if I can come up with anything like that, that is, if that
> would suffice?
For that specific problem, as long as the radix tree can be made to work
while non-preemptible, I'm fine :-)
I'm still worried by other cases where things expect GFP_ATOMIC to work
at any time.
Ben.
next prev parent reply other threads:[~2007-11-13 10:23 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-09 18:10 [PATCH, RFC] improved hacks to allow -rt to run kernbench on POWER Paul E. McKenney
2007-11-09 20:52 ` Benjamin Herrenschmidt
2007-11-09 22:07 ` Paul E. McKenney
2007-11-11 3:59 ` Benjamin Herrenschmidt
2007-11-11 14:45 ` Steven Rostedt
2007-11-11 20:48 ` Benjamin Herrenschmidt
2007-11-12 17:05 ` Paul E. McKenney
2007-11-12 19:15 ` Paul E. McKenney
2007-11-12 21:12 ` Benjamin Herrenschmidt
2007-11-13 9:10 ` Peter Zijlstra
2007-11-13 9:43 ` Benjamin Herrenschmidt [this message]
2007-11-13 10:05 ` Peter Zijlstra
2007-11-13 10:59 ` Peter Zijlstra
2007-11-13 11:09 ` Benjamin Herrenschmidt
2007-11-10 1:18 ` Nick Piggin
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