Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-28 Thread Eliezer Tamir 

On 28/05/2013 16:38, Eric Dumazet wrote:

On Tue, 2013-05-28 at 11:03 +0300, Eliezer Tamir wrote:


With an atomic we don't need the RTNL in any of the napi_id functions.
One less thing to worry about when we try to remove the RTNL.


OK but we'll need something to protect the lists against concurrent
insert/deletes.

A spinlock or a mutex.


OK
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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-28 Thread Eric Dumazet 
On Tue, 2013-05-28 at 11:03 +0300, Eliezer Tamir wrote:

> With an atomic we don't need the RTNL in any of the napi_id functions.
> One less thing to worry about when we try to remove the RTNL.

OK but we'll need something to protect the lists against concurrent
insert/deletes.

A spinlock or a mutex.



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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-28 Thread Eliezer Tamir 

On 28/05/2013 03:28, Eric Dumazet wrote:

On Mon, 2013-05-27 at 10:44 +0300, Eliezer Tamir wrote:

+extern void napi_hash_add(struct napi_struct *napi);
+
+/**
+ * napi_hash_del - remove a NAPI from blobal table


global


Thank you
(my typing is almost as bad as my spelling, please don't tell my mom)


@@ -166,6 +167,10 @@ static struct list_head offload_base __read_mostly;
  DEFINE_RWLOCK(dev_base_lock);
  EXPORT_SYMBOL(dev_base_lock);

+atomic_t napi_gen_id;


Not sure we need an atomic, we are protected by RTNL anyway.


With an atomic we don't need the RTNL in any of the napi_id functions.
One less thing to worry about when we try to remove the RTNL.

-Eliezer
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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-28 Thread Eliezer Tamir 

On 28/05/2013 03:28, Eric Dumazet wrote:

On Mon, 2013-05-27 at 10:44 +0300, Eliezer Tamir wrote:

+extern void napi_hash_add(struct napi_struct *napi);
+
+/**
+ * napi_hash_del - remove a NAPI from blobal table


global


Thank you
(my typing is almost as bad as my spelling, please don't tell my mom)


@@ -166,6 +167,10 @@ static struct list_head offload_base __read_mostly;
  DEFINE_RWLOCK(dev_base_lock);
  EXPORT_SYMBOL(dev_base_lock);

+atomic_t napi_gen_id;


Not sure we need an atomic, we are protected by RTNL anyway.


With an atomic we don't need the RTNL in any of the napi_id functions.
One less thing to worry about when we try to remove the RTNL.

-Eliezer
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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-28 Thread Eric Dumazet 
On Tue, 2013-05-28 at 11:03 +0300, Eliezer Tamir wrote:

 With an atomic we don't need the RTNL in any of the napi_id functions.
 One less thing to worry about when we try to remove the RTNL.

OK but we'll need something to protect the lists against concurrent
insert/deletes.

A spinlock or a mutex.



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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-28 Thread Eliezer Tamir 

On 28/05/2013 16:38, Eric Dumazet wrote:

On Tue, 2013-05-28 at 11:03 +0300, Eliezer Tamir wrote:


With an atomic we don't need the RTNL in any of the napi_id functions.
One less thing to worry about when we try to remove the RTNL.


OK but we'll need something to protect the lists against concurrent
insert/deletes.

A spinlock or a mutex.


OK
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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-27 Thread Eric Dumazet 
On Mon, 2013-05-27 at 10:44 +0300, Eliezer Tamir wrote:
> Adds a napi_id and a hashing mechanism to lookup a napi by id.
> This will be used by subsequent patches to implement low latency
> Ethernet device polling.
> Based on a code sample by Eric Dumazet.
> 
> Signed-off-by: Eliezer Tamir 
> ---
> 
>  include/linux/netdevice.h |   29 +
>  net/core/dev.c|   44 
>  2 files changed, 73 insertions(+), 0 deletions(-)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index ea7b6bc..d1ec8b1 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -324,12 +324,15 @@ struct napi_struct {
>   struct sk_buff  *gro_list;
>   struct sk_buff  *skb;
>   struct list_headdev_list;
> + struct hlist_node   napi_hash_node;
> + int napi_id;
>  };
>  
>  enum {
>   NAPI_STATE_SCHED,   /* Poll is scheduled */
>   NAPI_STATE_DISABLE, /* Disable pending */
>   NAPI_STATE_NPSVC,   /* Netpoll - don't dequeue from poll_list */
> + NAPI_STATE_HASHED,  /* In NAPI hash */
>  };
>  
>  enum gro_result {
> @@ -446,6 +449,32 @@ extern void __napi_complete(struct napi_struct *n);
>  extern void napi_complete(struct napi_struct *n);
>  
>  /**
> + *   napi_hash_add - add a NAPI to global hashtable
> + *   @napi: napi context
> + *
> + * generate a new napi_id and store a @napi under it in napi_hash
> + */
> +extern void napi_hash_add(struct napi_struct *napi);
> +
> +/**
> + *   napi_hash_del - remove a NAPI from blobal table

global

> + *   @napi: napi context
> + *
> + * Warning: caller must observe rcu grace period
> + * before freeing memory containing @NAPI

 @napi

> + */
> +extern void napi_hash_del(struct napi_struct *napi);
> +
> +/**
> + *   napi_by_is - lookup a NAPI by napi_id

napi_by_id

> + *   @napi_id: hashed napi_id
> + *
> + * lookup napi_id in napi_hash table

 @napi_id

> + * must be called under rcu_read_lock()
> + */
> +extern struct napi_struct *napi_by_id(int napi_id);
> +
> +/**
>   *   napi_disable - prevent NAPI from scheduling
>   *   @n: napi context
>   *
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 50c02de..283ab14 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -129,6 +129,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  #include "net-sysfs.h"
>  
> @@ -166,6 +167,10 @@ static struct list_head offload_base __read_mostly;
>  DEFINE_RWLOCK(dev_base_lock);
>  EXPORT_SYMBOL(dev_base_lock);
>  
> +atomic_t napi_gen_id;

Not sure we need an atomic, we are protected by RTNL anyway.

> +
> +DEFINE_HASHTABLE(napi_hash, 8);
> +
>  seqcount_t devnet_rename_seq;
>  
>  static inline void dev_base_seq_inc(struct net *net)
> @@ -4113,6 +4118,45 @@ void napi_complete(struct napi_struct *n)
>  }
>  EXPORT_SYMBOL(napi_complete);
>  
> +void napi_hash_add(struct napi_struct *napi)
> +{
> + if (!test_and_set_bit(NAPI_STATE_HASHED, >state)) {
> +
> + /* 0 is not a valid id */
> + napi->napi_id = 0;
> + while (!napi->napi_id)
> + napi->napi_id = atomic_inc_return(_gen_id);
> +
> + hlist_add_head_rcu(>napi_hash_node,
> + _hash[napi->napi_id % HASH_SIZE(napi_hash)]);
> + }
> +}
> +EXPORT_SYMBOL_GPL(napi_hash_add);
> +
> +/* Warning : caller is responsible to make sure rcu grace period
> + * is respected before freeing memory containing @napi
> + */
> +void napi_hash_del(struct napi_struct *napi)
> +{
> + if (test_and_clear_bit(NAPI_STATE_HASHED, >state))
> + hlist_del_rcu(>napi_hash_node);
> +}
> +EXPORT_SYMBOL_GPL(napi_hash_del);
> +
> +/* must be called under rcu_read_lock(), as we dont take a reference */
> +struct napi_struct *napi_by_id(int napi_id)
> +{
> + unsigned int hash = napi_id % HASH_SIZE(napi_hash);
> + struct napi_struct *napi;
> +
> + hlist_for_each_entry_rcu(napi, _hash[hash], napi_hash_node)
> + if (napi->napi_id == napi_id)
> + return napi;
> +
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(napi_by_id);
> +
>  void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
>   int (*poll)(struct napi_struct *, int), int weight)
>  {
> 


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[PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-27 Thread Eliezer Tamir 
Adds a napi_id and a hashing mechanism to lookup a napi by id.
This will be used by subsequent patches to implement low latency
Ethernet device polling.
Based on a code sample by Eric Dumazet.

Signed-off-by: Eliezer Tamir 
---

 include/linux/netdevice.h |   29 +
 net/core/dev.c|   44 
 2 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ea7b6bc..d1ec8b1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -324,12 +324,15 @@ struct napi_struct {
struct sk_buff  *gro_list;
struct sk_buff  *skb;
struct list_headdev_list;
+   struct hlist_node   napi_hash_node;
+   int napi_id;
 };
 
 enum {
NAPI_STATE_SCHED,   /* Poll is scheduled */
NAPI_STATE_DISABLE, /* Disable pending */
NAPI_STATE_NPSVC,   /* Netpoll - don't dequeue from poll_list */
+   NAPI_STATE_HASHED,  /* In NAPI hash */
 };
 
 enum gro_result {
@@ -446,6 +449,32 @@ extern void __napi_complete(struct napi_struct *n);
 extern void napi_complete(struct napi_struct *n);
 
 /**
+ * napi_hash_add - add a NAPI to global hashtable
+ * @napi: napi context
+ *
+ * generate a new napi_id and store a @napi under it in napi_hash
+ */
+extern void napi_hash_add(struct napi_struct *napi);
+
+/**
+ * napi_hash_del - remove a NAPI from blobal table
+ * @napi: napi context
+ *
+ * Warning: caller must observe rcu grace period
+ * before freeing memory containing @NAPI
+ */
+extern void napi_hash_del(struct napi_struct *napi);
+
+/**
+ * napi_by_is - lookup a NAPI by napi_id
+ * @napi_id: hashed napi_id
+ *
+ * lookup napi_id in napi_hash table
+ * must be called under rcu_read_lock()
+ */
+extern struct napi_struct *napi_by_id(int napi_id);
+
+/**
  * napi_disable - prevent NAPI from scheduling
  * @n: napi context
  *
diff --git a/net/core/dev.c b/net/core/dev.c
index 50c02de..283ab14 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -129,6 +129,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #include "net-sysfs.h"
 
@@ -166,6 +167,10 @@ static struct list_head offload_base __read_mostly;
 DEFINE_RWLOCK(dev_base_lock);
 EXPORT_SYMBOL(dev_base_lock);
 
+atomic_t napi_gen_id;
+
+DEFINE_HASHTABLE(napi_hash, 8);
+
 seqcount_t devnet_rename_seq;
 
 static inline void dev_base_seq_inc(struct net *net)
@@ -4113,6 +4118,45 @@ void napi_complete(struct napi_struct *n)
 }
 EXPORT_SYMBOL(napi_complete);
 
+void napi_hash_add(struct napi_struct *napi)
+{
+   if (!test_and_set_bit(NAPI_STATE_HASHED, >state)) {
+
+   /* 0 is not a valid id */
+   napi->napi_id = 0;
+   while (!napi->napi_id)
+   napi->napi_id = atomic_inc_return(_gen_id);
+
+   hlist_add_head_rcu(>napi_hash_node,
+   _hash[napi->napi_id % HASH_SIZE(napi_hash)]);
+   }
+}
+EXPORT_SYMBOL_GPL(napi_hash_add);
+
+/* Warning : caller is responsible to make sure rcu grace period
+ * is respected before freeing memory containing @napi
+ */
+void napi_hash_del(struct napi_struct *napi)
+{
+   if (test_and_clear_bit(NAPI_STATE_HASHED, >state))
+   hlist_del_rcu(>napi_hash_node);
+}
+EXPORT_SYMBOL_GPL(napi_hash_del);
+
+/* must be called under rcu_read_lock(), as we dont take a reference */
+struct napi_struct *napi_by_id(int napi_id)
+{
+   unsigned int hash = napi_id % HASH_SIZE(napi_hash);
+   struct napi_struct *napi;
+
+   hlist_for_each_entry_rcu(napi, _hash[hash], napi_hash_node)
+   if (napi->napi_id == napi_id)
+   return napi;
+
+   return NULL;
+}
+EXPORT_SYMBOL_GPL(napi_by_id);
+
 void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
int (*poll)(struct napi_struct *, int), int weight)
 {

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[PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-27 Thread Eliezer Tamir 
Adds a napi_id and a hashing mechanism to lookup a napi by id.
This will be used by subsequent patches to implement low latency
Ethernet device polling.
Based on a code sample by Eric Dumazet.

Signed-off-by: Eliezer Tamir eliezer.ta...@linux.intel.com
---

 include/linux/netdevice.h |   29 +
 net/core/dev.c|   44 
 2 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ea7b6bc..d1ec8b1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -324,12 +324,15 @@ struct napi_struct {
struct sk_buff  *gro_list;
struct sk_buff  *skb;
struct list_headdev_list;
+   struct hlist_node   napi_hash_node;
+   int napi_id;
 };
 
 enum {
NAPI_STATE_SCHED,   /* Poll is scheduled */
NAPI_STATE_DISABLE, /* Disable pending */
NAPI_STATE_NPSVC,   /* Netpoll - don't dequeue from poll_list */
+   NAPI_STATE_HASHED,  /* In NAPI hash */
 };
 
 enum gro_result {
@@ -446,6 +449,32 @@ extern void __napi_complete(struct napi_struct *n);
 extern void napi_complete(struct napi_struct *n);
 
 /**
+ * napi_hash_add - add a NAPI to global hashtable
+ * @napi: napi context
+ *
+ * generate a new napi_id and store a @napi under it in napi_hash
+ */
+extern void napi_hash_add(struct napi_struct *napi);
+
+/**
+ * napi_hash_del - remove a NAPI from blobal table
+ * @napi: napi context
+ *
+ * Warning: caller must observe rcu grace period
+ * before freeing memory containing @NAPI
+ */
+extern void napi_hash_del(struct napi_struct *napi);
+
+/**
+ * napi_by_is - lookup a NAPI by napi_id
+ * @napi_id: hashed napi_id
+ *
+ * lookup napi_id in napi_hash table
+ * must be called under rcu_read_lock()
+ */
+extern struct napi_struct *napi_by_id(int napi_id);
+
+/**
  * napi_disable - prevent NAPI from scheduling
  * @n: napi context
  *
diff --git a/net/core/dev.c b/net/core/dev.c
index 50c02de..283ab14 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -129,6 +129,7 @@
 #include linux/inetdevice.h
 #include linux/cpu_rmap.h
 #include linux/static_key.h
+#include linux/hashtable.h
 
 #include net-sysfs.h
 
@@ -166,6 +167,10 @@ static struct list_head offload_base __read_mostly;
 DEFINE_RWLOCK(dev_base_lock);
 EXPORT_SYMBOL(dev_base_lock);
 
+atomic_t napi_gen_id;
+
+DEFINE_HASHTABLE(napi_hash, 8);
+
 seqcount_t devnet_rename_seq;
 
 static inline void dev_base_seq_inc(struct net *net)
@@ -4113,6 +4118,45 @@ void napi_complete(struct napi_struct *n)
 }
 EXPORT_SYMBOL(napi_complete);
 
+void napi_hash_add(struct napi_struct *napi)
+{
+   if (!test_and_set_bit(NAPI_STATE_HASHED, napi-state)) {
+
+   /* 0 is not a valid id */
+   napi-napi_id = 0;
+   while (!napi-napi_id)
+   napi-napi_id = atomic_inc_return(napi_gen_id);
+
+   hlist_add_head_rcu(napi-napi_hash_node,
+   napi_hash[napi-napi_id % HASH_SIZE(napi_hash)]);
+   }
+}
+EXPORT_SYMBOL_GPL(napi_hash_add);
+
+/* Warning : caller is responsible to make sure rcu grace period
+ * is respected before freeing memory containing @napi
+ */
+void napi_hash_del(struct napi_struct *napi)
+{
+   if (test_and_clear_bit(NAPI_STATE_HASHED, napi-state))
+   hlist_del_rcu(napi-napi_hash_node);
+}
+EXPORT_SYMBOL_GPL(napi_hash_del);
+
+/* must be called under rcu_read_lock(), as we dont take a reference */
+struct napi_struct *napi_by_id(int napi_id)
+{
+   unsigned int hash = napi_id % HASH_SIZE(napi_hash);
+   struct napi_struct *napi;
+
+   hlist_for_each_entry_rcu(napi, napi_hash[hash], napi_hash_node)
+   if (napi-napi_id == napi_id)
+   return napi;
+
+   return NULL;
+}
+EXPORT_SYMBOL_GPL(napi_by_id);
+
 void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
int (*poll)(struct napi_struct *, int), int weight)
 {

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Re: [PATCH v5 net-next 1/5] net: add napi_id and hash

2013-05-27 Thread Eric Dumazet 
On Mon, 2013-05-27 at 10:44 +0300, Eliezer Tamir wrote:
 Adds a napi_id and a hashing mechanism to lookup a napi by id.
 This will be used by subsequent patches to implement low latency
 Ethernet device polling.
 Based on a code sample by Eric Dumazet.
 
 Signed-off-by: Eliezer Tamir eliezer.ta...@linux.intel.com
 ---
 
  include/linux/netdevice.h |   29 +
  net/core/dev.c|   44 
  2 files changed, 73 insertions(+), 0 deletions(-)
 
 diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
 index ea7b6bc..d1ec8b1 100644
 --- a/include/linux/netdevice.h
 +++ b/include/linux/netdevice.h
 @@ -324,12 +324,15 @@ struct napi_struct {
   struct sk_buff  *gro_list;
   struct sk_buff  *skb;
   struct list_headdev_list;
 + struct hlist_node   napi_hash_node;
 + int napi_id;
  };
  
  enum {
   NAPI_STATE_SCHED,   /* Poll is scheduled */
   NAPI_STATE_DISABLE, /* Disable pending */
   NAPI_STATE_NPSVC,   /* Netpoll - don't dequeue from poll_list */
 + NAPI_STATE_HASHED,  /* In NAPI hash */
  };
  
  enum gro_result {
 @@ -446,6 +449,32 @@ extern void __napi_complete(struct napi_struct *n);
  extern void napi_complete(struct napi_struct *n);
  
  /**
 + *   napi_hash_add - add a NAPI to global hashtable
 + *   @napi: napi context
 + *
 + * generate a new napi_id and store a @napi under it in napi_hash
 + */
 +extern void napi_hash_add(struct napi_struct *napi);
 +
 +/**
 + *   napi_hash_del - remove a NAPI from blobal table

global

 + *   @napi: napi context
 + *
 + * Warning: caller must observe rcu grace period
 + * before freeing memory containing @NAPI

 @napi

 + */
 +extern void napi_hash_del(struct napi_struct *napi);
 +
 +/**
 + *   napi_by_is - lookup a NAPI by napi_id

napi_by_id

 + *   @napi_id: hashed napi_id
 + *
 + * lookup napi_id in napi_hash table

 @napi_id

 + * must be called under rcu_read_lock()
 + */
 +extern struct napi_struct *napi_by_id(int napi_id);
 +
 +/**
   *   napi_disable - prevent NAPI from scheduling
   *   @n: napi context
   *
 diff --git a/net/core/dev.c b/net/core/dev.c
 index 50c02de..283ab14 100644
 --- a/net/core/dev.c
 +++ b/net/core/dev.c
 @@ -129,6 +129,7 @@
  #include linux/inetdevice.h
  #include linux/cpu_rmap.h
  #include linux/static_key.h
 +#include linux/hashtable.h
  
  #include net-sysfs.h
  
 @@ -166,6 +167,10 @@ static struct list_head offload_base __read_mostly;
  DEFINE_RWLOCK(dev_base_lock);
  EXPORT_SYMBOL(dev_base_lock);
  
 +atomic_t napi_gen_id;

Not sure we need an atomic, we are protected by RTNL anyway.

 +
 +DEFINE_HASHTABLE(napi_hash, 8);
 +
  seqcount_t devnet_rename_seq;
  
  static inline void dev_base_seq_inc(struct net *net)
 @@ -4113,6 +4118,45 @@ void napi_complete(struct napi_struct *n)
  }
  EXPORT_SYMBOL(napi_complete);
  
 +void napi_hash_add(struct napi_struct *napi)
 +{
 + if (!test_and_set_bit(NAPI_STATE_HASHED, napi-state)) {
 +
 + /* 0 is not a valid id */
 + napi-napi_id = 0;
 + while (!napi-napi_id)
 + napi-napi_id = atomic_inc_return(napi_gen_id);
 +
 + hlist_add_head_rcu(napi-napi_hash_node,
 + napi_hash[napi-napi_id % HASH_SIZE(napi_hash)]);
 + }
 +}
 +EXPORT_SYMBOL_GPL(napi_hash_add);
 +
 +/* Warning : caller is responsible to make sure rcu grace period
 + * is respected before freeing memory containing @napi
 + */
 +void napi_hash_del(struct napi_struct *napi)
 +{
 + if (test_and_clear_bit(NAPI_STATE_HASHED, napi-state))
 + hlist_del_rcu(napi-napi_hash_node);
 +}
 +EXPORT_SYMBOL_GPL(napi_hash_del);
 +
 +/* must be called under rcu_read_lock(), as we dont take a reference */
 +struct napi_struct *napi_by_id(int napi_id)
 +{
 + unsigned int hash = napi_id % HASH_SIZE(napi_hash);
 + struct napi_struct *napi;
 +
 + hlist_for_each_entry_rcu(napi, napi_hash[hash], napi_hash_node)
 + if (napi-napi_id == napi_id)
 + return napi;
 +
 + return NULL;
 +}
 +EXPORT_SYMBOL_GPL(napi_by_id);
 +
  void netif_napi_add(struct net_device *dev, struct napi_struct *napi,
   int (*poll)(struct napi_struct *, int), int weight)
  {
 


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