Re: [PATCH] - Fix get_model_name() for mixed cpu type systems

From: Stephane Eranian <eranian_at_hpl.hp.com>
Date: 2006-10-19 07:44:13
Jack,

The perfmon subsystem will not work correctly if you mix
Madison and Montecito in the same box. And there is not an
easy way to make it work with such configuration. Performance
counters are different between the two models.

The only thing we could do, is to detect such condition
and default to the architectured PMU.


On Wed, Oct 18, 2006 at 04:25:59PM -0500, Jack Steiner wrote:
> 
> If a system consists of mixed processor types, kmalloc()
> can be called before the per-cpu data page is initialized. 
> If the slab contains sufficient memory, then kmalloc() works
> ok. However, if the slabs are empty, slab calls the memory
> allocator. This requires per-cpu data (NODE_DATA()) & the
> cpu dies.
> 
> 	Signed-off-by: Jack Steiner <steiner@sgi.com>
> 
> 
> 
> 
> Index: linux/arch/ia64/kernel/setup.c
> ===================================================================
> --- linux.orig/arch/ia64/kernel/setup.c	2006-10-18 15:49:49.000000000 -0500
> +++ linux/arch/ia64/kernel/setup.c	2006-10-18 16:19:18.261790796 -0500
> @@ -643,12 +643,14 @@ struct seq_operations cpuinfo_op = {
>  	.show =		show_cpuinfo
>  };
>  
> -static char brandname[128];
> +#define MAX_BRANDS	4
> +static char brandname[MAX_BRANDS][128];
>  
>  static char * __cpuinit
>  get_model_name(__u8 family, __u8 model)
>  {
>  	char brand[128];
> +	int i;
>  
>  	if (ia64_pal_get_brand_info(brand)) {
>  		if (family == 0x7)
> @@ -660,12 +662,14 @@ get_model_name(__u8 family, __u8 model)
>  		} else
>  			memcpy(brand, "Unknown", 8);
>  	}
> -	if (brandname[0] == '\0')
> -		return strcpy(brandname, brand);
> -	else if (strcmp(brandname, brand) == 0)
> -		return brandname;
> -	else
> -		return kstrdup(brand, GFP_KERNEL);
> +	for (i = 0; i < MAX_BRANDS; i++)
> +		if (strcmp(brandname[i], brand) == 0)
> +			return brandname[i];
> +	for (i = 0; i < MAX_BRANDS; i++)
> +		if (brandname[i][0] == '\0')
> +			return strcpy(brandname[i], brand);
> +	BUG();
> +	return NULL;	/* quiet compiler */
>  }
>  
>  static void __cpuinit
> -
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-- 

-Stephane
-
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Received on Thu Oct 19 07:45:14 2006

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