linux-kernel - Re: [patch 03/41] cpu alloc: Use cpu allocator instead of the builtin modules per cpu allocator

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Date:	Fri, 30 May 2008 16:08:01 +1000
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Christoph Lameter <clameter@....com>
Cc:	akpm@...ux-foundation.org, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org, David Miller <davem@...emloft.net>,
	Eric Dumazet <dada1@...mosbay.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Travis <travis@....com>
Subject: Re: [patch 03/41] cpu alloc: Use cpu allocator instead of the builtin modules per cpu allocator

On Friday 30 May 2008 13:56:23 Christoph Lameter wrote:
> --- linux-2.6.orig/kernel/module.c	2008-05-29 17:57:39.825214766 -0700
> +++ linux-2.6/kernel/module.c	2008-05-29 18:00:50.496815514 -0700
> @@ -314,121 +314,6 @@ static struct module *find_module(const
>  	return NULL;
>  }

115 lines removed... This is my favourite part of the series so far :)

>  	if (mod->percpu)
> -		percpu_modfree(mod->percpu);
> +		cpu_free(mod->percpu, mod->percpu_size);

Hmm, does cpu_free(NULL, 0) do something?  Seems like it shouldn't, for 
symmetry with free().

> +		if (align > PAGE_SIZE) {
> +			printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
> +			mod->name, align, PAGE_SIZE);
> +			align = PAGE_SIZE;
> +		}
> +		percpu = cpu_alloc(size, GFP_KERNEL|__GFP_ZERO, align);
> +		if (!percpu)
> +			printk(KERN_WARNING "Could not allocate %lu bytes percpu data\n",
> +										size);
>  		if (!percpu) {
>  			err = -ENOMEM;
>  			goto free_mod;

OK, we've *never* had a report of the per-cpu alignment message, so I'd be 
happy to pass that through to cpu_alloc() and have it fail.  Also, the if 
(!percpu) cases should be combined.

>   free_percpu:
>  	if (percpu)
> -		percpu_modfree(percpu);
> +		cpu_free(percpu, percpu_size);

As above.

> +	goal = __per_cpu_size;

Where did __per_cpu_size come from?  I missed it in the earlier patches...

Thanks,
Rusty.
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