Re: [Xen-devel] [PATCH v9 12/25] x86: refactor psr: L3 CAT: set value: implement cos id picking flow.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 31.03.17 at 14:40, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> On 17-03-31 04:19:49, Jan Beulich wrote:
>> >>> On 31.03.17 at 11:12, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> > On 17-03-31 02:47:25, Jan Beulich wrote:
>> >> >>> On 30.03.17 at 14:10, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
>> >> > I think you can check v9 codes here:
>> >> > https://github.com/yisun-git/xen/tree/l2_cat_v9 
>> >> 
>> >> Looking at this made me notice that cat_get_old_val() passes a
>> >> bogus literal 0 to cat_get_val(), which needs taking care of too.
>> >> One option I can see is for each feature to make available an
>> >> array of type enum cbm_type, with cos_num elements. The order
>> >> would match that of the order of values in their arrays. This will
>> > 
>> > Sorry, not very clear your meaning. How to do that? Could you please
>> > provide pieces of codes? Thanks!
>> 
>> I'm sorry, but I'm afraid I don't see how I would reasonably supply
>> code here without taking over your series altogether (which I don't
>> intend to do). What is unclear with, at the example of CDP, you
>> needing to add an array at initialization time, slot 0 of which holds
>> PSR_CBM_TYPE_L3_DATA and slot 1 PSR_CBM_TYPE_L3_CODE (or
>> the other way around). Granted I was wrong with the type of the
>> array (as the above aren't enum psr_feat_type enumerators, but
>> enum cbm_type ones), but I think the basic idea should have been
>> clear anyway: You need to provide a way for generic code to pass
>> suitable type information into ->get_val().
>> 
> May I change the 'get_val()' parameter 'enum cbm_type' to a generic type
> 'unsigned int' to make it be a flexible type,  and then combine feature
> type with cos_num together as a flag to indicate which feature it is,
> which value to get and distinguish it with cbm_type? For example:
> 
> #define CDP_GATHER_BOTH_DATA ( PSR_SOCKET_L3_CDP << 16 )
> #define CDP_GATHER_BOTH_CODE ( PSR_SOCKET_L3_CDP << 16 + 1 )
> static void l3_cdp_get_val(const struct feat_node *feat, unsigned int cos,
>                            unsigned int type, uint32_t *val)
> {
>     switch ( type )
>     {
>     case PSR_CBM_TYPE_L3_DATA:
>     case CDP_GATHER_BOTH_DATA:
>         *val = get_cdp_data(feat, cos);
>         break;
>     case PSR_CBM_TYPE_L3_CODE:
>     case CDP_GATHER_BOTH_CODE:
>         *val = get_cdp_code(feat, cos);
>         break;
>     }
> }

The two case labels are still indicative of unnecessary redundancy
(and, even right now only highly theoretical, risk of collisions). What's
wrong with the model I've proposed?

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel