diff mbox series

[bpf-next,2/9] net: add SO_BUSY_POLL_BUDGET socket option

Message ID 20201112114041.131998-3-bjorn.topel@gmail.com
State Superseded
Headers show
Series Introduce preferred busy-polling | expand

Commit Message

Björn Töpel Nov. 12, 2020, 11:40 a.m. UTC 
From: Björn Töpel <bjorn.topel@intel.com>

This option lets a user set a per socket NAPI budget for
busy-polling. If the options is not set, it will use the default of 8.

Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
---
 arch/alpha/include/uapi/asm/socket.h  |  1 +
 arch/mips/include/uapi/asm/socket.h   |  1 +
 arch/parisc/include/uapi/asm/socket.h |  1 +
 arch/sparc/include/uapi/asm/socket.h  |  1 +
 fs/eventpoll.c                        |  3 ++-
 include/net/busy_poll.h               |  7 +++++--
 include/net/sock.h                    |  1 +
 include/uapi/asm-generic/socket.h     |  1 +
 net/core/dev.c                        | 21 ++++++++++-----------
 net/core/sock.c                       | 10 ++++++++++
 10 files changed, 33 insertions(+), 14 deletions(-)

Comments

Eric Dumazet Nov. 12, 2020, 2:36 p.m. UTC | #1 
On Thu, Nov 12, 2020 at 12:41 PM Björn Töpel <bjorn.topel@gmail.com> wrote:
>
> From: Björn Töpel <bjorn.topel@intel.com>
>
> This option lets a user set a per socket NAPI budget for
> busy-polling. If the options is not set, it will use the default of 8.
>
> Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
> ---
>

...

>  #else /* CONFIG_NET_RX_BUSY_POLL */
>  static inline unsigned long net_busy_loop_on(void)
> @@ -106,7 +108,8 @@ static inline void sk_busy_loop(struct sock *sk, int nonblock)
>
>         if (napi_id >= MIN_NAPI_ID)
>                 napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
> -                              READ_ONCE(sk->sk_prefer_busy_poll));
> +                              READ_ONCE(sk->sk_prefer_busy_poll),
> +                              sk->sk_busy_poll_budget ?: BUSY_POLL_BUDGET);

Please use :

       READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET

Because sk_busy_loop() is usually called without socket lock being held.

This will prevent yet another KCSAN report.

>  #endif
>  }
>

...

> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -1165,6 +1165,16 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
>                 else
>                         sk->sk_prefer_busy_poll = valbool;
>                 break;
> +       case SO_BUSY_POLL_BUDGET:
> +               if (val > sk->sk_busy_poll_budget && !capable(CAP_NET_ADMIN)) {
> +                       ret = -EPERM;
> +               } else {
> +                       if (val < 0)

               if (val < 0 || val > (u16)~0)

> +                               ret = -EINVAL;
> +                       else
> +                               sk->sk_busy_poll_budget = val;


                               WRITE_ONCE(sk->sk_busy_poll_budget, val);

> +               }
> +               break;
>  #endif
>
>         case SO_MAX_PACING_RATE:
> --
> 2.27.0
>
Björn Töpel Nov. 12, 2020, 2:45 p.m. UTC | #2 
On 2020-11-12 15:36, Eric Dumazet wrote:
> On Thu, Nov 12, 2020 at 12:41 PM Björn Töpel <bjorn.topel@gmail.com> wrote:
>>
>> From: Björn Töpel <bjorn.topel@intel.com>
>>
>> This option lets a user set a per socket NAPI budget for
>> busy-polling. If the options is not set, it will use the default of 8.
>>
>> Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
>> ---
>>
> 
> ...
> 
>>   #else /* CONFIG_NET_RX_BUSY_POLL */
>>   static inline unsigned long net_busy_loop_on(void)
>> @@ -106,7 +108,8 @@ static inline void sk_busy_loop(struct sock *sk, int nonblock)
>>
>>          if (napi_id >= MIN_NAPI_ID)
>>                  napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
>> -                              READ_ONCE(sk->sk_prefer_busy_poll));
>> +                              READ_ONCE(sk->sk_prefer_busy_poll),
>> +                              sk->sk_busy_poll_budget ?: BUSY_POLL_BUDGET);
> 
> Please use :
> 
>         READ_ONCE(sk->sk_busy_poll_budget) ?: BUSY_POLL_BUDGET
> 
> Because sk_busy_loop() is usually called without socket lock being held.
> 
> This will prevent yet another KCSAN report.
> 
>>   #endif
>>   }
>>
> 
> ...
> 
>> --- a/net/core/sock.c
>> +++ b/net/core/sock.c
>> @@ -1165,6 +1165,16 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
>>                  else
>>                          sk->sk_prefer_busy_poll = valbool;
>>                  break;
>> +       case SO_BUSY_POLL_BUDGET:
>> +               if (val > sk->sk_busy_poll_budget && !capable(CAP_NET_ADMIN)) {
>> +                       ret = -EPERM;
>> +               } else {
>> +                       if (val < 0)
> 
>                 if (val < 0 || val > (u16)~0)
> 
>> +                               ret = -EINVAL;
>> +                       else
>> +                               sk->sk_busy_poll_budget = val;
> 
> 
>                                 WRITE_ONCE(sk->sk_busy_poll_budget, val);
>

Thanks for the review! I'll address it all.
diff mbox series

Patch

diff --git a/arch/alpha/include/uapi/asm/socket.h b/arch/alpha/include/uapi/asm/socket.h
index 538359642554..57420356ce4c 100644
--- a/arch/alpha/include/uapi/asm/socket.h
+++ b/arch/alpha/include/uapi/asm/socket.h
@@ -125,6 +125,7 @@ 
 #define SO_DETACH_REUSEPORT_BPF 68
 
 #define SO_PREFER_BUSY_POLL	69
+#define SO_BUSY_POLL_BUDGET	70
 
 #if !defined(__KERNEL__)
 
diff --git a/arch/mips/include/uapi/asm/socket.h b/arch/mips/include/uapi/asm/socket.h
index e406e73b5e6e..2d949969313b 100644
--- a/arch/mips/include/uapi/asm/socket.h
+++ b/arch/mips/include/uapi/asm/socket.h
@@ -136,6 +136,7 @@ 
 #define SO_DETACH_REUSEPORT_BPF 68
 
 #define SO_PREFER_BUSY_POLL	69
+#define SO_BUSY_POLL_BUDGET	70
 
 #if !defined(__KERNEL__)
 
diff --git a/arch/parisc/include/uapi/asm/socket.h b/arch/parisc/include/uapi/asm/socket.h
index 1bc46200889d..f60904329bbc 100644
--- a/arch/parisc/include/uapi/asm/socket.h
+++ b/arch/parisc/include/uapi/asm/socket.h
@@ -117,6 +117,7 @@ 
 #define SO_DETACH_REUSEPORT_BPF 0x4042
 
 #define SO_PREFER_BUSY_POLL	0x4043
+#define SO_BUSY_POLL_BUDGET	0x4044
 
 #if !defined(__KERNEL__)
 
diff --git a/arch/sparc/include/uapi/asm/socket.h b/arch/sparc/include/uapi/asm/socket.h
index 99688cf673a4..848a22fbac20 100644
--- a/arch/sparc/include/uapi/asm/socket.h
+++ b/arch/sparc/include/uapi/asm/socket.h
@@ -118,6 +118,7 @@ 
 #define SO_DETACH_REUSEPORT_BPF  0x0047
 
 #define SO_PREFER_BUSY_POLL	 0x0048
+#define SO_BUSY_POLL_BUDGET	 0x0049
 
 #if !defined(__KERNEL__)
 
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index e11fab3a0b9e..73c346e503d7 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -397,7 +397,8 @@  static void ep_busy_loop(struct eventpoll *ep, int nonblock)
 	unsigned int napi_id = READ_ONCE(ep->napi_id);
 
 	if ((napi_id >= MIN_NAPI_ID) && net_busy_loop_on())
-		napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false);
+		napi_busy_loop(napi_id, nonblock ? NULL : ep_busy_loop_end, ep, false,
+			       BUSY_POLL_BUDGET);
 }
 
 static inline void ep_reset_busy_poll_napi_id(struct eventpoll *ep)
diff --git a/include/net/busy_poll.h b/include/net/busy_poll.h
index 0292b8353d7e..b4f653cc15a7 100644
--- a/include/net/busy_poll.h
+++ b/include/net/busy_poll.h
@@ -23,6 +23,8 @@ 
  */
 #define MIN_NAPI_ID ((unsigned int)(NR_CPUS + 1))
 
+#define BUSY_POLL_BUDGET 8
+
 #ifdef CONFIG_NET_RX_BUSY_POLL
 
 struct napi_struct;
@@ -43,7 +45,7 @@  bool sk_busy_loop_end(void *p, unsigned long start_time);
 
 void napi_busy_loop(unsigned int napi_id,
 		    bool (*loop_end)(void *, unsigned long),
-		    void *loop_end_arg, bool prefer_busy_poll);
+		    void *loop_end_arg, bool prefer_busy_poll, u16 budget);
 
 #else /* CONFIG_NET_RX_BUSY_POLL */
 static inline unsigned long net_busy_loop_on(void)
@@ -106,7 +108,8 @@  static inline void sk_busy_loop(struct sock *sk, int nonblock)
 
 	if (napi_id >= MIN_NAPI_ID)
 		napi_busy_loop(napi_id, nonblock ? NULL : sk_busy_loop_end, sk,
-			       READ_ONCE(sk->sk_prefer_busy_poll));
+			       READ_ONCE(sk->sk_prefer_busy_poll),
+			       sk->sk_busy_poll_budget ?: BUSY_POLL_BUDGET);
 #endif
 }
 
diff --git a/include/net/sock.h b/include/net/sock.h
index 716960a15e83..1ddfb4a2dac2 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -481,6 +481,7 @@  struct sock {
 	kuid_t			sk_uid;
 #ifdef CONFIG_NET_RX_BUSY_POLL
 	u8			sk_prefer_busy_poll;
+	u16			sk_busy_poll_budget;
 #endif
 	struct pid		*sk_peer_pid;
 	const struct cred	*sk_peer_cred;
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index 7dd02408b7ce..4dcd13d097a9 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -120,6 +120,7 @@ 
 #define SO_DETACH_REUSEPORT_BPF 68
 
 #define SO_PREFER_BUSY_POLL	69
+#define SO_BUSY_POLL_BUDGET	70
 
 #if !defined(__KERNEL__)
 
diff --git a/net/core/dev.c b/net/core/dev.c
index 49015b059549..33c67004f2ad 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6492,8 +6492,6 @@  static struct napi_struct *napi_by_id(unsigned int napi_id)
 
 #if defined(CONFIG_NET_RX_BUSY_POLL)
 
-#define BUSY_POLL_BUDGET 8
-
 static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
 {
 	if (!skip_schedule) {
@@ -6513,7 +6511,8 @@  static void __busy_poll_stop(struct napi_struct *napi, bool skip_schedule)
 	clear_bit(NAPI_STATE_SCHED, &napi->state);
 }
 
-static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool prefer_busy_poll)
+static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool prefer_busy_poll,
+			   u16 budget)
 {
 	bool skip_schedule = false;
 	unsigned long timeout;
@@ -6545,21 +6544,21 @@  static void busy_poll_stop(struct napi_struct *napi, void *have_poll_lock, bool
 	/* All we really want here is to re-enable device interrupts.
 	 * Ideally, a new ndo_busy_poll_stop() could avoid another round.
 	 */
-	rc = napi->poll(napi, BUSY_POLL_BUDGET);
+	rc = napi->poll(napi, budget);
 	/* We can't gro_normal_list() here, because napi->poll() might have
 	 * rearmed the napi (napi_complete_done()) in which case it could
 	 * already be running on another CPU.
 	 */
-	trace_napi_poll(napi, rc, BUSY_POLL_BUDGET);
+	trace_napi_poll(napi, rc, budget);
 	netpoll_poll_unlock(have_poll_lock);
-	if (rc == BUSY_POLL_BUDGET)
+	if (rc == budget)
 		__busy_poll_stop(napi, skip_schedule);
 	local_bh_enable();
 }
 
 void napi_busy_loop(unsigned int napi_id,
 		    bool (*loop_end)(void *, unsigned long),
-		    void *loop_end_arg, bool prefer_busy_poll)
+		    void *loop_end_arg, bool prefer_busy_poll, u16 budget)
 {
 	unsigned long start_time = loop_end ? busy_loop_current_time() : 0;
 	int (*napi_poll)(struct napi_struct *napi, int budget);
@@ -6602,8 +6601,8 @@  void napi_busy_loop(unsigned int napi_id,
 			have_poll_lock = netpoll_poll_lock(napi);
 			napi_poll = napi->poll;
 		}
-		work = napi_poll(napi, BUSY_POLL_BUDGET);
-		trace_napi_poll(napi, work, BUSY_POLL_BUDGET);
+		work = napi_poll(napi, budget);
+		trace_napi_poll(napi, work, budget);
 		gro_normal_list(napi);
 count:
 		if (work > 0)
@@ -6616,7 +6615,7 @@  void napi_busy_loop(unsigned int napi_id,
 
 		if (unlikely(need_resched())) {
 			if (napi_poll)
-				busy_poll_stop(napi, have_poll_lock, prefer_busy_poll);
+				busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
 			preempt_enable();
 			rcu_read_unlock();
 			cond_resched();
@@ -6627,7 +6626,7 @@  void napi_busy_loop(unsigned int napi_id,
 		cpu_relax();
 	}
 	if (napi_poll)
-		busy_poll_stop(napi, have_poll_lock, prefer_busy_poll);
+		busy_poll_stop(napi, have_poll_lock, prefer_busy_poll, budget);
 	preempt_enable();
 out:
 	rcu_read_unlock();
diff --git a/net/core/sock.c b/net/core/sock.c
index 248f6a763661..e08d5a6ae9d4 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1165,6 +1165,16 @@  int sock_setsockopt(struct socket *sock, int level, int optname,
 		else
 			sk->sk_prefer_busy_poll = valbool;
 		break;
+	case SO_BUSY_POLL_BUDGET:
+		if (val > sk->sk_busy_poll_budget && !capable(CAP_NET_ADMIN)) {
+			ret = -EPERM;
+		} else {
+			if (val < 0)
+				ret = -EINVAL;
+			else
+				sk->sk_busy_poll_budget = val;
+		}
+		break;
 #endif
 
 	case SO_MAX_PACING_RATE: