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 15:22, <yi.y.sun@xxxxxxxxxxxxxxx> wrote:
> On 17-03-31 06:51:07, Jan Beulich wrote:
>> >>> 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?
>> 
> Oh, sorry. I did not understand your proposal just now so I provided another
> solution.
> 
> After reading your suggestion again, I think your meaing is below in codes:
> 
> struct feat_props {
> ...
>     unsigned int cos_num;
>     enum cbm_type cos_to_type[2];
> ...
> }
> 
> static void cat_init_feature(...)
> {
> ...
>     case PSR_SOCKET_L3_CDP:
>         feat->props->cos_to_type[0] = PSR_CBM_TYPE_L3_DATA;
>         feat->props->cos_to_type[1] = PSR_CBM_TYPE_L3_CODE;
> ...
> }
> 
> Then, in functions to iterate 'cos_num', we can input 'cos_to_type[i]'. 

Yes (albeit I'd call the array field just "type").

Jan


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