From: Rusty Russell <rusty@rustcorp.com.au>
To: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH -v2] use per cpu data for single cpu ipi calls
Date: Fri, 30 Jan 2009 12:25:48 +1030
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Cc: Steven Rostedt <rostedt@goodmis.org>,
       Peter Zijlstra <peterz@infradead.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>, npiggin@suse.de,
       Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       Arjan van de Ven <arjan@infradead.org>, jens.axboe@oracle.com
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On Friday 30 January 2009 04:38:23 Linus Torvalds wrote:
> 
> On Thu, 29 Jan 2009, Steven Rostedt wrote:
> > 
> > Actually, we are locking against the destination CPU.
> 
> Oh.
> 
> THAT'S JUST INCOMPETENT.
> 
> What the *fuck* is the point of having per-CPU data, and then using it for 
> the wrong CPU?

Maybe we made it too easy to declare and use per-cpu data?

Could we use an nr_cpu_ids array?  Yes, it needs alloc at boot somewhere, but
it avoids collateral damage to other percpu data (and please don't suggest DEFINE_PER_CPU_SHARED_ALIGNED: that's just antisocial).

Thanks,
Rusty.
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