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net: rename low latency sockets functions to busy poll

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Rename functions in include/net/ll_poll.h to busy wait.
Clarify documentation about expected power use increase.
Rename POLL_LL to POLL_BUSY_LOOP.
Add need_resched() testing to poll/select busy loops.

Note, that in select and poll can_busy_poll is dynamic and is
updated continuously to reflect the existence of supported
sockets with valid queue information.

Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eliezer Tamir
2013-07-08 19:25:45 -07:00
committed by David S. Miller
parent c7e8e8a8f7
commit cbf55001b2
7 changed files with 80 additions and 61 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/net/ll_poll.h
+24 -22
View File
@@ -37,9 +37,9 @@ extern unsigned int sysctl_net_ll_poll __read_mostly;
#define LL_FLUSH_FAILED -1
#define LL_FLUSH_BUSY -2
static inline unsigned int ll_get_flag(void)
static inline bool net_busy_loop_on(void)
{
return sysctl_net_ll_poll ? POLL_LL : 0;
return sysctl_net_ll_poll;
}
/* a wrapper to make debug_smp_processor_id() happy
@@ -47,7 +47,7 @@ static inline unsigned int ll_get_flag(void)
* we only care that the average is bounded
*/
#ifdef CONFIG_DEBUG_PREEMPT
static inline u64 ll_sched_clock(void)
static inline u64 busy_loop_sched_clock(void)
{
u64 rc;
@@ -58,7 +58,7 @@ static inline u64 ll_sched_clock(void)
return rc;
}
#else /* CONFIG_DEBUG_PREEMPT */
static inline u64 ll_sched_clock(void)
static inline u64 busy_loop_sched_clock(void)
{
return sched_clock();
}
@@ -67,7 +67,7 @@ static inline u64 ll_sched_clock(void)
/* we don't mind a ~2.5% imprecision so <<10 instead of *1000
* sk->sk_ll_usec is a u_int so this can't overflow
*/
static inline u64 ll_sk_run_time(struct sock *sk)
static inline u64 sk_busy_loop_end_time(struct sock *sk)
{
return (u64)ACCESS_ONCE(sk->sk_ll_usec) << 10;
}
@@ -75,27 +75,29 @@ static inline u64 ll_sk_run_time(struct sock *sk)
/* in poll/select we use the global sysctl_net_ll_poll value
* only call sched_clock() if enabled
*/
static inline u64 ll_run_time(void)
static inline u64 busy_loop_end_time(void)
{
return (u64)ACCESS_ONCE(sysctl_net_ll_poll) << 10;
}
/* if flag is not set we don't need to know the time */
static inline u64 ll_start_time(unsigned int flag)
/* if flag is not set we don't need to know the time
* so we want to avoid a potentially expensive sched_clock()
*/
static inline u64 busy_loop_start_time(unsigned int flag)
{
return flag ? ll_sched_clock() : 0;
return flag ? busy_loop_sched_clock() : 0;
}
static inline bool sk_valid_ll(struct sock *sk)
static inline bool sk_can_busy_loop(struct sock *sk)
{
return sk->sk_ll_usec && sk->sk_napi_id &&
!need_resched() && !signal_pending(current);
}
/* careful! time_in_range64 will evaluate now twice */
static inline bool can_poll_ll(u64 start_time, u64 run_time)
static inline bool busy_loop_range(u64 start_time, u64 run_time)
{
u64 now = ll_sched_clock();
u64 now = busy_loop_sched_clock();
return time_in_range64(now, start_time, start_time + run_time);
}
@@ -103,10 +105,10 @@ static inline bool can_poll_ll(u64 start_time, u64 run_time)
/* when used in sock_poll() nonblock is known at compile time to be true
* so the loop and end_time will be optimized out
*/
static inline bool sk_poll_ll(struct sock *sk, int nonblock)
static inline bool sk_busy_loop(struct sock *sk, int nonblock)
{
u64 start_time = ll_start_time(!nonblock);
u64 run_time = ll_sk_run_time(sk);
u64 start_time = busy_loop_start_time(!nonblock);
u64 end_time = sk_busy_loop_end_time(sk);
const struct net_device_ops *ops;
struct napi_struct *napi;
int rc = false;
@@ -137,7 +139,7 @@ static inline bool sk_poll_ll(struct sock *sk, int nonblock)
LINUX_MIB_LOWLATENCYRXPACKETS, rc);
} while (!nonblock && skb_queue_empty(&sk->sk_receive_queue) &&
can_poll_ll(start_time, run_time));
busy_loop_range(start_time, end_time));
rc = !skb_queue_empty(&sk->sk_receive_queue);
out:
@@ -158,27 +160,27 @@ static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
}
#else /* CONFIG_NET_LL_RX_POLL */
static inline unsigned long ll_get_flag(void)
static inline unsigned long net_busy_loop_on(void)
{
return 0;
}
static inline u64 ll_start_time(unsigned int flag)
static inline u64 busy_loop_start_time(unsigned int flag)
{
return 0;
}
static inline u64 ll_run_time(void)
static inline u64 busy_loop_end_time(void)
{
return 0;
}
static inline bool sk_valid_ll(struct sock *sk)
static inline bool sk_can_busy_loop(struct sock *sk)
{
return false;
}
static inline bool sk_poll_ll(struct sock *sk, int nonblock)
static inline bool sk_busy_poll(struct sock *sk, int nonblock)
{
return false;
}
@@ -191,7 +193,7 @@ static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb)
{
}
static inline bool can_poll_ll(u64 start_time, u64 run_time)
static inline bool busy_loop_range(u64 start_time, u64 run_time)
{
return false;
}
include/uapi/asm-generic/poll.h
+1 -1
View File
@@ -30,7 +30,7 @@
#define POLLFREE 0x4000 /* currently only for epoll */
#define POLL_LL 0x8000
#define POLL_BUSY_LOOP 0x8000
struct pollfd {
int fd;