Date: Wed, 7 Aug 2013 11:33:45 -0700
From: Kent Overstreet <kmo@daterainc.com>
To: Christoph Lameter <cl@gentwo.org>
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        Tejun Heo <tj@kernel.org>, Oleg Nesterov <oleg@redhat.com>,
        Ingo Molnar <mingo@redhat.com>, Andi Kleen <andi@firstfloor.org>,
        Jens Axboe <axboe@kernel.dk>,
        "Nicholas A. Bellinger" <nab@linux-iscsi.org>
Subject: Re: [PATCH 04/10] idr: Percpu ida
Message-ID: <20130807183345.GA11612@kmo-pixel>
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On Wed, Aug 07, 2013 at 05:56:34PM +0000, Christoph Lameter wrote:
> On Wed, 7 Aug 2013, Kent Overstreet wrote:
> 
> > +{
> > +	DEFINE_WAIT(wait);
> > +	struct percpu_ida_cpu *tags;
> > +	unsigned long flags;
> > +	unsigned this_cpu;
> > +	int tag;
> > +
> > +	local_irq_save(flags);
> 
> > +	this_cpu = smp_processor_id();
> > +	tags = per_cpu_ptr(pool->tag_cpu, this_cpu);
> 
> tags = this_cpu_ptr(pool->tag_cpu);

I was breaking it apart because I was using this_cpu elsewhere too - for
the bitmap of which cpus have non empty freelists.

Or is this_cpu_ptr() doing something smarter than per_cpu_ptr(ptr,
smp_processer_id())? There's so many variants I'm not 100% sure they're
the same.
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