From: Denis Vlasenko <vda@ilport.com.ua>
To: Christoph Lameter <clameter@engr.sgi.com>
Subject: Re: Make kzalloc a macro
Date: Sat, 24 Sep 2005 13:52:54 +0300
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Cc: akpm@osdl.org, Nick Piggin <nickpiggin@yahoo.com.au>,
       "David S. Miller" <davem@davemloft.net>, ioe-lkml@rameria.dem,
       linux-kernel@vger.kernel.org
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On Friday 23 September 2005 18:58, Christoph Lameter wrote:
> How about this patch making kzalloc a macro?
> 
> ---
> 
> Make kzalloc a macro and use __GFP_ZERO for zeroed slab allocations
> 
> kzalloc is right now a function call. The optimization that the kmalloc macro
> provides does not work for kzalloc invocations. kmalloc also determines the
> slab to use at compile time and fails the compilation if the size is too big.
> kzalloc cannot do not.
> 
>  
> -extern void *kzalloc(size_t, unsigned int __nocast);
> +#define kzalloc(__size, __flags) kmalloc(__size, (__flags) | __GFP_ZERO)

Why macro and not an inline function?

> +static inline void *obj_checkout(kmem_cache_t *cachep, unsigned int __nocast flags, void *objp)
> +{
> +	if (likely(objp)) {
> +		objp = cache_alloc_debugcheck_after(cachep, flags, objp,
> +					__builtin_return_address(0));
> +		if (unlikely(flags & __GFP_ZERO))

Why unlikely?

> +			memset(objp, 0, obj_reallen(cachep));
> +		else
> +			prefetchw(objp);
> +	}
> +	return objp;
> +}
--
vda
-
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