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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: Eliezer Tamir <eliezer.tamir@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eliezer Tamir 2013-06-14 16:33:35 +03:00 committed by David S. Miller
parent eb6db62282
commit 9a3c71aa80
2 changed files with 17 additions and 17 deletions
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33
include/net/ll_poll.h
View File

@ -21,10 +21,6 @@
* e1000-devel Mailing List <e1000-devel@lists.sourceforge.net> * e1000-devel Mailing List <e1000-devel@lists.sourceforge.net>
*/ */
/*
* For now this depends on CONFIG_X86_TSC
*/
#ifndef _LINUX_NET_LL_POLL_H #ifndef _LINUX_NET_LL_POLL_H
#define _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_FAILED -1
#define LL_FLUSH_BUSY -2 #define LL_FLUSH_BUSY -2
/* we don't mind a ~2.5% imprecision */ /* we can use sched_clock() because we don't care much about precision
#define TSC_MHZ (tsc_khz >> 10) * we only care that the average is bounded
*/
static inline cycles_t ll_end_time(void) static inline u64 ll_end_time(void)
{ {
return (cycles_t)TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll) u64 end_time = ACCESS_ONCE(sysctl_net_ll_poll);
+ get_cycles();
/* 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) 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); !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(), return !time_after64(sched_clock(), end_time);
(unsigned long)end_time);
} }
static inline bool sk_poll_ll(struct sock *sk, int nonblock) static inline bool sk_poll_ll(struct sock *sk, int nonblock)
{ {
cycles_t end_time = ll_end_time();
const struct net_device_ops *ops; const struct net_device_ops *ops;
u64 end_time = ll_end_time();
struct napi_struct *napi; struct napi_struct *napi;
int rc = false; 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 */ #else /* CONFIG_NET_LL_RX_POLL */
static inline cycles_t ll_end_time(void) static inline u64 ll_end_time(void)
{ {
return 0; 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; return false;
} }

1
net/Kconfig
View File

@ -245,7 +245,6 @@ config NETPRIO_CGROUP
config NET_LL_RX_POLL config NET_LL_RX_POLL
bool "Low Latency Receive Poll" bool "Low Latency Receive Poll"
depends on X86_TSC
default n default n
---help--- ---help---
Support Low Latency Receive Queue Poll. Support Low Latency Receive Queue Poll.