Re: [Xen-devel] [PATCH v2 3/7] x86: detect and initialize Intel CAT feature

[Tim Deegan <tim@xxxxxxx>]

Hi, 

At 18:41 +0800 on 19 Mar (1426790491), Chao Peng wrote:
> @@ -62,8 +84,15 @@ static void __init parse_psr_param(char *s)
>              *val_str++ = '\0';
>  
>          parse_psr_bool(s, val_str, "cmt", PSR_CMT);
> -        if ( val_str && !strcmp(s, "rmid_max") )
> -            opt_rmid_max = simple_strtoul(val_str, NULL, 0);
> +        parse_psr_bool(s, val_str, "cat", PSR_CAT);
> +
> +        if ( val_str )
> +        {
> +            if ( !strcmp(s, "rmid_max") )
> +                opt_rmid_max = simple_strtoul(val_str, NULL, 0);
> +            else if ( !strcmp(s, "num_sockets") )
> +                opt_num_sockets = simple_strtoul(val_str, NULL, 0);

This is an unfortunate interface for the user.  Can Xen not find out
how many sockets there are without needing to be told?

Also, per-socket data seems like a more generally useful thing that
other features will want to use.  Do you think future Intel cache
features will also have per-socket state?  If so, I think it would be
better to extend the per-cpu data system to handle per-socket areas.

Cheers,

Tim.

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