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Commit 9a3c71aa authored by Eliezer Tamir's avatar Eliezer Tamir Committed by David S. Miller
Browse files

net: convert low latency sockets to sched_clock() 



Use sched_clock() instead of get_cycles().
We can use sched_clock() because we don't care much about accuracy.
Remove the dependency on X86_TSC

Signed-off-by: default avatarEliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent eb6db622

include/net/ll_poll.h

+17 −16
Original line number Diff line number Diff line
@@ -21,10 +21,6 @@ 
 * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>

 */



/*

 * For now this depends on CONFIG_X86_TSC

 */



#ifndef _LINUX_NET_LL_POLL_H

#define _LINUX_NET_LL_POLL_H
@@ -40,13 +36,19 @@ extern unsigned int sysctl_net_ll_poll __read_mostly; 
#define LL_FLUSH_FAILED		-1

#define LL_FLUSH_BUSY		-2



/* we don't mind a ~2.5% imprecision */

#define TSC_MHZ (tsc_khz >> 10)



static inline cycles_t ll_end_time(void)

/* we can use sched_clock() because we don't care much about precision

 * we only care that the average is bounded

 */

static inline u64 ll_end_time(void)

{

	return (cycles_t)TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll)

			+ get_cycles();

	u64 end_time = ACCESS_ONCE(sysctl_net_ll_poll);



	/* we don't mind a ~2.5% imprecision

	 * sysctl_net_ll_poll is a u_int so this can't overflow

	 */

	end_time = (end_time << 10) + sched_clock();



	return end_time;

}



static inline bool sk_valid_ll(struct sock *sk)
@@ -55,16 +57,15 @@ static inline bool sk_valid_ll(struct sock *sk) 
	       !need_resched() && !signal_pending(current);

}



static inline bool can_poll_ll(cycles_t end_time)

static inline bool can_poll_ll(u64 end_time)

{

	return !time_after((unsigned long)get_cycles(),

			    (unsigned long)end_time);

	return !time_after64(sched_clock(), end_time);

}



static inline bool sk_poll_ll(struct sock *sk, int nonblock)

{

	cycles_t end_time = ll_end_time();

	const struct net_device_ops *ops;

	u64 end_time = ll_end_time();

	struct napi_struct *napi;

	int rc = false;
@@ -117,7 +118,7 @@ static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb) 


#else /* CONFIG_NET_LL_RX_POLL */



static inline cycles_t ll_end_time(void)

static inline u64 ll_end_time(void)

{

	return 0;

}
@@ -140,7 +141,7 @@ static inline void sk_mark_ll(struct sock *sk, struct sk_buff *skb) 
{

}



static inline bool can_poll_ll(cycles_t end_time)

static inline bool can_poll_ll(u64 end_time)

{

	return false;

}

net/Kconfig

+0 −1
Original line number Diff line number Diff line
@@ -245,7 +245,6 @@ config NETPRIO_CGROUP 


config NET_LL_RX_POLL

	bool "Low Latency Receive Poll"

	depends on X86_TSC

	default n

	---help---

	  Support Low Latency Receive Queue Poll.