[v1,1/2] interconnect: Add support for path tags

Message ID 20190208172152.1807-2-georgi.djakov@linaro.org
State New
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  • [v1,1/2] interconnect: Add support for path tags
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Commit Message

Georgi Djakov Feb. 8, 2019, 5:21 p.m.
Consumers may have use cases with different bandwidth requirements based
on the system or driver state. The consumer driver can append a specific
tag to the path and pass this information to the interconnect platform
driver to do the aggregation based on this state.

Introduce icc_set_tag() function that will allow the consumers to append
an optional tag to each path. The aggregation of these tagged paths is
platform specific.

Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

---
 drivers/interconnect/core.c           | 27 +++++++++++++++++++++++----
 drivers/interconnect/qcom/sdm845.c    |  2 +-
 include/linux/interconnect-provider.h |  4 ++--
 include/linux/interconnect.h          |  5 +++++
 4 files changed, 31 insertions(+), 7 deletions(-)

Comments

Evan Green March 8, 2019, 6:40 p.m. | #1
On Fri, Feb 8, 2019 at 9:21 AM Georgi Djakov <georgi.djakov@linaro.org> wrote:
>

> Consumers may have use cases with different bandwidth requirements based

> on the system or driver state. The consumer driver can append a specific

> tag to the path and pass this information to the interconnect platform

> driver to do the aggregation based on this state.

>

> Introduce icc_set_tag() function that will allow the consumers to append

> an optional tag to each path. The aggregation of these tagged paths is

> platform specific.

>

> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

> ---

>  drivers/interconnect/core.c           | 27 +++++++++++++++++++++++----

>  drivers/interconnect/qcom/sdm845.c    |  2 +-

>  include/linux/interconnect-provider.h |  4 ++--

>  include/linux/interconnect.h          |  5 +++++

>  4 files changed, 31 insertions(+), 7 deletions(-)

>

> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c

> index 6005a1c189f6..31eacd0f5349 100644

> --- a/drivers/interconnect/core.c

> +++ b/drivers/interconnect/core.c

> @@ -42,10 +42,12 @@ struct icc_req {

>

>  /**

>   * struct icc_path - interconnect path structure

> + * @tag: path tag (optional)

>   * @num_nodes: number of hops (nodes)

>   * @reqs: array of the requests applicable to this path of nodes

>   */

>  struct icc_path {

> +       u32 tag;

>         size_t num_nodes;

>         struct icc_req reqs[];

>  };

> @@ -206,7 +208,7 @@ static struct icc_path *path_find(struct device *dev, struct icc_node *src,

>   * implementing its own aggregate() function.

>   */

>

> -static int aggregate_requests(struct icc_node *node)

> +static int aggregate_requests(struct icc_node *node, u32 tag)

>  {

>         struct icc_provider *p = node->provider;

>         struct icc_req *r;

> @@ -215,7 +217,7 @@ static int aggregate_requests(struct icc_node *node)

>         node->peak_bw = 0;


For my suggestion in patch 2, this is where you'd need the callback to
reset the SLEEP/WAKE shadow aggregation buckets that the provider is
keeping, since the core just reset the values here. I wonder if you'd
want to pass the &node->avg_bw and &node->peak_bw in with this
callback as well... not sure if that's useful. Something like:

        if (p->begin_aggregation)
                p->begin_aggregation(node);

>

>         hlist_for_each_entry(r, &node->req_list, req_node)

> -               p->aggregate(node, r->avg_bw, r->peak_bw,

> +               p->aggregate(node, tag, r->avg_bw, r->peak_bw,

>                              &node->avg_bw, &node->peak_bw);


Wait I'm confused. The tag is associated with a particular path. But
now aren't you looping over all the other requests and coloring them
with whatever tag this is? Don't you need to store the tag with the
request, and then pass r->tag for each r rather than the tag from
whichever request happened to initiate the re-aggregation?

>

>         return 0;

> @@ -396,6 +398,23 @@ struct icc_path *of_icc_get(struct device *dev, const char *name)

>  }

>  EXPORT_SYMBOL_GPL(of_icc_get);

>
Georgi Djakov March 20, 2019, 5:10 p.m. | #2
Hi Evan,

On 3/8/19 20:40, Evan Green wrote:
> On Fri, Feb 8, 2019 at 9:21 AM Georgi Djakov <georgi.djakov@linaro.org> wrote:

>>

>> Consumers may have use cases with different bandwidth requirements based

>> on the system or driver state. The consumer driver can append a specific

>> tag to the path and pass this information to the interconnect platform

>> driver to do the aggregation based on this state.

>>

>> Introduce icc_set_tag() function that will allow the consumers to append

>> an optional tag to each path. The aggregation of these tagged paths is

>> platform specific.

>>

>> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>

>> ---

>>  drivers/interconnect/core.c           | 27 +++++++++++++++++++++++----

>>  drivers/interconnect/qcom/sdm845.c    |  2 +-

>>  include/linux/interconnect-provider.h |  4 ++--

>>  include/linux/interconnect.h          |  5 +++++

>>  4 files changed, 31 insertions(+), 7 deletions(-)

>>

>> diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c

>> index 6005a1c189f6..31eacd0f5349 100644

>> --- a/drivers/interconnect/core.c

>> +++ b/drivers/interconnect/core.c

>> @@ -42,10 +42,12 @@ struct icc_req {

>>

>>  /**

>>   * struct icc_path - interconnect path structure

>> + * @tag: path tag (optional)

>>   * @num_nodes: number of hops (nodes)

>>   * @reqs: array of the requests applicable to this path of nodes

>>   */

>>  struct icc_path {

>> +       u32 tag;

>>         size_t num_nodes;

>>         struct icc_req reqs[];

>>  };

>> @@ -206,7 +208,7 @@ static struct icc_path *path_find(struct device *dev, struct icc_node *src,

>>   * implementing its own aggregate() function.

>>   */

>>

>> -static int aggregate_requests(struct icc_node *node)

>> +static int aggregate_requests(struct icc_node *node, u32 tag)

>>  {

>>         struct icc_provider *p = node->provider;

>>         struct icc_req *r;

>> @@ -215,7 +217,7 @@ static int aggregate_requests(struct icc_node *node)

>>         node->peak_bw = 0;

> 

> For my suggestion in patch 2, this is where you'd need the callback to

> reset the SLEEP/WAKE shadow aggregation buckets that the provider is

> keeping, since the core just reset the values here. I wonder if you'd

> want to pass the &node->avg_bw and &node->peak_bw in with this

> callback as well... not sure if that's useful. Something like:

> 

>         if (p->begin_aggregation)

>                 p->begin_aggregation(node);


Currently this seems only Qcom specific, so i would prefer to wait and
see if there are similar need for other platforms before adding a new
callback. IMO the best option for now would be to reset the values in
the platform driver after they are committed.

>>

>>         hlist_for_each_entry(r, &node->req_list, req_node)

>> -               p->aggregate(node, r->avg_bw, r->peak_bw,

>> +               p->aggregate(node, tag, r->avg_bw, r->peak_bw,

>>                              &node->avg_bw, &node->peak_bw);

> 

> Wait I'm confused. The tag is associated with a particular path. But

> now aren't you looping over all the other requests and coloring them

> with whatever tag this is? Don't you need to store the tag with the

> request, and then pass r->tag for each r rather than the tag from

> whichever request happened to initiate the re-aggregation?


Yes indeed. I think i am missing a patch here. Thanks for catching it!

BR,
Georgi

>>

>>         return 0;

>> @@ -396,6 +398,23 @@ struct icc_path *of_icc_get(struct device *dev, const char *name)

>>  }

>>  EXPORT_SYMBOL_GPL(of_icc_get);

>>

Patch

diff --git a/drivers/interconnect/core.c b/drivers/interconnect/core.c
index 6005a1c189f6..31eacd0f5349 100644
--- a/drivers/interconnect/core.c
+++ b/drivers/interconnect/core.c
@@ -42,10 +42,12 @@  struct icc_req {
 
 /**
  * struct icc_path - interconnect path structure
+ * @tag: path tag (optional)
  * @num_nodes: number of hops (nodes)
  * @reqs: array of the requests applicable to this path of nodes
  */
 struct icc_path {
+	u32 tag;
 	size_t num_nodes;
 	struct icc_req reqs[];
 };
@@ -206,7 +208,7 @@  static struct icc_path *path_find(struct device *dev, struct icc_node *src,
  * implementing its own aggregate() function.
  */
 
-static int aggregate_requests(struct icc_node *node)
+static int aggregate_requests(struct icc_node *node, u32 tag)
 {
 	struct icc_provider *p = node->provider;
 	struct icc_req *r;
@@ -215,7 +217,7 @@  static int aggregate_requests(struct icc_node *node)
 	node->peak_bw = 0;
 
 	hlist_for_each_entry(r, &node->req_list, req_node)
-		p->aggregate(node, r->avg_bw, r->peak_bw,
+		p->aggregate(node, tag, r->avg_bw, r->peak_bw,
 			     &node->avg_bw, &node->peak_bw);
 
 	return 0;
@@ -396,6 +398,23 @@  struct icc_path *of_icc_get(struct device *dev, const char *name)
 }
 EXPORT_SYMBOL_GPL(of_icc_get);
 
+/**
+ * icc_set_tag() - set an optional tag on a path
+ * @path: the path we want to tag
+ * @tag: the tag value
+ *
+ * This function allows consumers to append a tag to the path, so that a
+ * different aggregation could be done based on this tag.
+ */
+void icc_set_tag(struct icc_path *path, u32 tag)
+{
+	if (!path)
+		return;
+
+	path->tag = tag;
+}
+EXPORT_SYMBOL_GPL(icc_set_tag);
+
 /**
  * icc_set_bw() - set bandwidth constraints on an interconnect path
  * @path: reference to the path returned by icc_get()
@@ -434,7 +453,7 @@  int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 		path->reqs[i].peak_bw = peak_bw;
 
 		/* aggregate requests for this node */
-		aggregate_requests(node);
+		aggregate_requests(node, path->tag);
 	}
 
 	ret = apply_constraints(path);
@@ -446,7 +465,7 @@  int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 			node = path->reqs[i].node;
 			path->reqs[i].avg_bw = old_avg;
 			path->reqs[i].peak_bw = old_peak;
-			aggregate_requests(node);
+			aggregate_requests(node, path->tag);
 		}
 		apply_constraints(path);
 	}
diff --git a/drivers/interconnect/qcom/sdm845.c b/drivers/interconnect/qcom/sdm845.c
index 4915b78da673..fb526004c82e 100644
--- a/drivers/interconnect/qcom/sdm845.c
+++ b/drivers/interconnect/qcom/sdm845.c
@@ -626,7 +626,7 @@  static void bcm_aggregate(struct qcom_icc_bcm *bcm)
 	bcm->dirty = false;
 }
 
-static int qcom_icc_aggregate(struct icc_node *node, u32 avg_bw,
+static int qcom_icc_aggregate(struct icc_node *node, u32 tag, u32 avg_bw,
 			      u32 peak_bw, u32 *agg_avg, u32 *agg_peak)
 {
 	size_t i;
diff --git a/include/linux/interconnect-provider.h b/include/linux/interconnect-provider.h
index 63caccadc2db..4ee19fd41568 100644
--- a/include/linux/interconnect-provider.h
+++ b/include/linux/interconnect-provider.h
@@ -45,8 +45,8 @@  struct icc_provider {
 	struct list_head	provider_list;
 	struct list_head	nodes;
 	int (*set)(struct icc_node *src, struct icc_node *dst);
-	int (*aggregate)(struct icc_node *node, u32 avg_bw, u32 peak_bw,
-			 u32 *agg_avg, u32 *agg_peak);
+	int (*aggregate)(struct icc_node *node, u32 tag, u32 avg_bw,
+			 u32 peak_bw, u32 *agg_avg, u32 *agg_peak);
 	struct icc_node* (*xlate)(struct of_phandle_args *spec, void *data);
 	struct device		*dev;
 	int			users;
diff --git a/include/linux/interconnect.h b/include/linux/interconnect.h
index dc25864755ba..d70a914cba11 100644
--- a/include/linux/interconnect.h
+++ b/include/linux/interconnect.h
@@ -30,6 +30,7 @@  struct icc_path *icc_get(struct device *dev, const int src_id,
 struct icc_path *of_icc_get(struct device *dev, const char *name);
 void icc_put(struct icc_path *path);
 int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw);
+void icc_set_tag(struct icc_path *path, u32 tag);
 
 #else
 
@@ -54,6 +55,10 @@  static inline int icc_set_bw(struct icc_path *path, u32 avg_bw, u32 peak_bw)
 	return 0;
 }
 
+static inline void icc_set_tag(struct icc_path *path, u32 tag)
+{
+}
+
 #endif /* CONFIG_INTERCONNECT */
 
 #endif /* __LINUX_INTERCONNECT_H */