Subject: Re: [RFC 1/3] Unified NMI delayed call mechanism
From: Peter Zijlstra <peterz@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>, Ingo Molnar <mingo@elte.hu>,
       "H.PeterA" <"nvin hpa"@zytor.com>, linux-kernel@vger.kernel.org,
       Chris Mason <chris.mason@oracle.com>
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Date: Fri, 18 Jun 2010 15:24:53 +0200
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On Fri, 2010-06-18 at 15:23 +0200, Andi Kleen wrote:
> On Fri, Jun 18, 2010 at 03:12:49PM +0200, Peter Zijlstra wrote:
> > On Fri, 2010-06-18 at 15:09 +0200, Andi Kleen wrote:
> > > > You generally want to pass more information along anyway, now your
> > > > callback function needs to go look for it. Much better to pass a
> > > > work_struct like thing around that is contained in the state it needs.
> > > 
> > > But how would you allocate the work queue in an NMI?
> > > 
> > > If it's only a single instance (like this bit) it can be always put
> > > into a per cpu variable.
> > 
> > Pre-allocate. For the perf-event stuff we use the perf_event allocated
> > at creation time. But yeah, per-cpu storage also works.
> 
> So you could just preallocate the bits instead ?

You mean the bits in your function array? Those are limited to 32 and
you'd need a secondary lookup to match them to your data object, not
very useful.


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