[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v8 03/24] x86: refactor psr: implement main data structures.
On Wed, Mar 01, 2017 at 01:10:02PM +0800, Yi Sun wrote: > On 17-02-28 11:58:59, Roger Pau Monn� wrote: > > On Wed, Feb 15, 2017 at 04:49:18PM +0800, Yi Sun wrote: > > > To construct an extendible framework, we need analyze PSR features > > > and abstract the common things and feature specific things. Then, > > > encapsulate them into different data structures. > > > > > > By analyzing PSR features, we can get below map. > > > +------+------+------+ > > > --------->| Dom0 | Dom1 | ... | > > > | +------+------+------+ > > > | | > > > |Dom ID | cos_id of domain > > > | V > > > | > > > +-----------------------------------------------------------------------------+ > > > User --------->| PSR > > > | > > > Socket ID | +--------------+---------------+---------------+ > > > | > > > | | Socket0 Info | Socket 1 Info | ... | > > > | > > > | +--------------+---------------+---------------+ > > > | > > > | | cos_id=0 cos_id=1 > > > ... | > > > | | > > > +-----------------------+-----------------------+-----------+ | > > > | |->Ref : | ref 0 | ref 1 > > > | ... | | > > > | | > > > +-----------------------+-----------------------+-----------+ | > > > | | > > > +-----------------------+-----------------------+-----------+ | > > > | |->L3 CAT: | cos 0 | cos 1 > > > | ... | | > > > | | > > > +-----------------------+-----------------------+-----------+ | > > > | | > > > +-----------------------+-----------------------+-----------+ | > > > | |->L2 CAT: | cos 0 | cos 1 > > > | ... | | > > > | | > > > +-----------------------+-----------------------+-----------+ | > > > | | > > > +-----------+-----------+-----------+-----------+-----------+ | > > > | |->CDP : | cos0 code | cos0 data | cos1 code | cos1 > > > data | ... | | > > > | > > > +-----------+-----------+-----------+-----------+-----------+ | > > > > > > +-----------------------------------------------------------------------------+ > > > > > > So, we need define a socket info data structure, 'struct > > > psr_socket_info' to manage information per socket. It contains a > > > reference count array according to COS ID and a feature list to > > > manage all features enabled. Every entry of the reference count > > > array is used to record how many domains are using the COS registers > > > according to the COS ID. For example, L3 CAT and L2 CAT are enabled, > > > Dom1 uses COS_ID=1 registers of both features to save CBM values, like > > > below. > > > +-------+-------+-------+-----+ > > > | COS 0 | COS 1 | COS 2 | ... | > > > +-------+-------+-------+-----+ > > > L3 CAT | 0x7ff | 0x1ff | ... | ... | > > > +-------+-------+-------+-----+ > > > L2 CAT | 0xff | 0xff | ... | ... | > > > +-------+-------+-------+-----+ > > > > > > If Dom2 has same CBM values, it can reuse these registers which COS_ID=1. > > > That means, both Dom1 and Dom2 use same COS registers(ID=1) to save same > > > L3/L2 values. So, the value ref[1] is 2 which means 2 domains are using > > > COS_ID 1. > > > > > > To manage a feature, we need define a feature node data structure, > > > 'struct feat_node', to manage feature's specific HW info, its callback > > > functions (all feature's specific behaviors are encapsulated into these > > > callback functions), and an array of all COS registers values of this > > > feature. > > > > > > CDP is a special feature which uses two entries of the array > > > for one COS ID. So, the number of CDP COS registers is the half of L3 > > > CAT. E.g. L3 CAT has 16 COS registers, then CDP has 8 COS registers if > > > it is enabled. CDP uses the COS registers array as below. > > > > > > > > > +-----------+-----------+-----------+-----------+-----------+ > > > CDP cos_reg_val[] index: | 0 | 1 | 2 | 3 > > > | ... | > > > > > > +-----------+-----------+-----------+-----------+-----------+ > > > value: | cos0 code | cos0 data | cos1 code | cos1 data > > > | ... | > > > > > > +-----------+-----------+-----------+-----------+-----------+ > > > > > > For more details, please refer SDM and patches to implement 'get value' > > > and > > > 'set value'. > > > > I would recommend that you merge this with a patch that actually makes use > > of > > this structures, or else it's hard to review it's usage IMHO. > > > Sorry for this. To make codes less and simpler in a patch, I split this patch > out to only show the data structures. I think I can merge it with next patch: > [PATCH v8 04/24] x86: refactor psr: implement CPU init and free flow. > > How do you think? Now that I've looked at the other patches this doesn't seem so abstract to me, I will leave that to the x86 maintainers, and whether they want to join it with some actual code or not. > > > +struct psr_socket_info { > > > + /* > > > + * It maps to values defined in 'enum psr_feat_type' below. Value in > > > 'enum > > > + * psr_feat_type' means the bit position. > > > + * bit 0: L3 CAT > > > + * bit 1: L3 CDP > > > + * bit 2: L2 CAT > > > + */ > > > + unsigned int feat_mask; > > > + unsigned int nr_feat; > > > + struct list_head feat_list; > > > > Isn't it a little bit overkill to use a list when there can only be a > > maximum > > of 3 features? (and the feat_mask is currently 32bits, so I guess you don't > > really foresee having more than 32 features). > > > > I would suggest using: > > > > struct feat_node *features[PSR_SOCKET_MAX_FEAT]; > > > > (PSR_SOCKET_MAX_FEAT comes from the expansion of the enum below). Then you > > can > > simply use the enum value of each feature as the position of it's > > corresponding > > feat_node into the array. > > > I really thought this before. But there may be different features enabled on > different sockets. For example, socket 0 enables L3 CAT and L2 CAT but socket > 1 > only supports L3 CAT. So, the feature array may be different for different > sockets. I think it is more complex to use array to handle all things than > list. Different sockets with different features enabled should still be fine. Each socket has a feat_mask, and you can use that to know whether a certain feature is enabled or not. What I was proposing is to make feat_node an array of pointers, so if a feature is not supported that specific pointer would be NULL (ie: if feat_mask & PSR_SOCKET_L3_CDP == 0, features[PSR_SOCKET_L3_CDP] == NULL). And then you can avoid all the list traversing code. > > > + unsigned int cos_ref[MAX_COS_REG_CNT]; > > > + spinlock_t ref_lock; > > > +}; > > > + > > > +enum psr_feat_type { > > > + PSR_SOCKET_L3_CAT = 0, > > > + PSR_SOCKET_L3_CDP, > > > + PSR_SOCKET_L2_CAT, > > PSR_SOCKET_MAX_FEAT, > > > +}; > > > + > > > +/* CAT/CDP HW info data structure. */ > > > +struct psr_cat_hw_info { > > > + unsigned int cbm_len; > > > + unsigned int cos_max; > > > +}; > > > + > > > +/* Encapsulate feature specific HW info here. */ > > > +struct feat_hw_info { > > > + union { > > > + struct psr_cat_hw_info l3_cat_info; > > > + }; > > > +}; > > > > Why don't you use an union here directly, instead of encapsulating an union > > inside of a struct? > > > > union feat_hw_info { > > struct psr_cat_hw_info l3_cat_info; > > }; > > > > > + > > > +struct feat_node; > > > + > > > +/* > > > + * This structure defines feature operation callback functions. Every > > > feature > > > + * enabled MUST implement such callback functions and register them to > > > ops. > > > + * > > > + * Feature specific behaviors will be encapsulated into these callback > > > + * functions. Then, the main flows will not be changed when introducing > > > a new > > > + * feature. > > > + */ > > > +struct feat_ops { > > > + /* get_cos_max is used to get feature's cos_max. */ > > > + unsigned int (*get_cos_max)(const struct feat_node *feat); > > > +}; > > > + > > > +/* > > > + * This structure represents one feature. > > > + * feature - Which feature it is. > > > + * feat_ops - Feature operation callback functions. > > > + * info - Feature HW info. > > > + * cos_reg_val - Array to store the values of COS registers. One entry > > > stores > > > + * the value of one COS register. > > > + * For L3 CAT and L2 CAT, one entry corresponds to one > > > COS_ID. > > > + * For CDP, two entries correspond to one COS_ID. E.g. > > > + * COS_ID=0 corresponds to cos_reg_val[0] (Data) and > > > + * cos_reg_val[1] (Code). > > > + * list - Feature list. > > > + */ > > > +struct feat_node { > > > + enum psr_feat_type feature; > > > > If you index them in an array with the key being psr_feat_type I don't think > > you need that field. > > > I need this to check if input type can match this feature, you can refer get > val or set val flow. Thanks! If you move to the array of pointers proposed above you no longer need this since you can just do features[PSR_SOCKET_L3_CAT] and get the pointer to the feat_node struct, the index into the array is going to be the feature type already. > > > + struct feat_ops ops; > > > > I would place the function hooks in this struct directly, instead of nesting > > them inside of another struct. The hooks AFAICT are shared between all the > > different PSR features. > > > Jan suggested this before in v4 patch. We have discussed this and Jan accepts > current implementation. The reason is below: > > "To facilitate the callback functions assignment for a feature, I defined > feature specific callback function ops like below. > > struct feat_ops l3_cat_ops = { > .init_feature = l3_cat_init_feature, > .get_max_cos_max = l3_cat_get_max_cos_max, > ...... > }; This should be constified as Jan already pointed out. I see that what I said before doesn't make sense, since you have both constant functions pointers (that can be shared across nodes), plus local node storage in this structure. Roger. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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