Date: Thu, 13 Nov 2008 14:58:46 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Yinghai Lu <yinghai@kernel.org>
Cc: mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com,
       linux-kernel@vger.kernel.org, travis@sgi.com
Subject: Re: [PATCH] sparse_irq aka dyn_irq v13
Message-Id: <20081113145846.bef2bb90.akpm@linux-foundation.org>
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On Thu, 13 Nov 2008 14:41:36 -0800
Yinghai Lu <yinghai@kernel.org> wrote:

> Andrew Morton wrote:
> 
> >> ...
> >>
> >>>> +static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];
> >>> Do these need to be 32-bit?  Maybe they'll fit in 16-bit, dunno.
> >>>
> >> struct irq_desc {
> >>         unsigned int            irq;
> >> #ifdef CONFIG_SPARSE_IRQ
> >>         struct list_head        list;
> >>         struct list_head        hash_entry;
> >>         struct timer_rand_state *timer_rand_state;
> >>         unsigned int            *kstat_irqs;
> > 
> > That doesn't address my question.
> > 
> > The above array can be very large.  Can we halve its size by using
> > 16-bit quantities?  Will this code ever encounter IRQ numbers larger
> > than 65536?
> > 
> 
> NR_CPUS=4096, NR_IRQS_LEGACY=16, and that array will be 256k bytes
> 
> later could change that alloc_bootmem, so NR_CPUS will be replaced to nr_cpu_ids

Do the entries in that array need to be 32-bit?
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