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net: avoid calling sched_clock when LLS is off

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Change Low Latency Sockets code for select and poll so that
when LLS is disabled sched_clock() is never called.

Also, avoid sending POLL_LL to sockets if disabled.

Reported-by: Andi Kleen <andi@firstfloor.org>
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
2013-06-28 15:59:35 +03:00
committed by David S. Miller
parent ad6276e0fe
commit 91e2fd3378
2 changed files with 22 additions and 6 deletions
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include/net/ll_poll.h
+15 -2
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@@ -37,6 +37,11 @@ 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)
{
return sysctl_net_ll_poll ? POLL_LL : 0;
}
/* a wrapper to make debug_smp_processor_id() happy
* we can use sched_clock() because we don't care much about precision
* we only care that the average is bounded
@@ -67,10 +72,14 @@ static inline u64 ll_sk_end_time(struct sock *sk)
return ((u64)ACCESS_ONCE(sk->sk_ll_usec) << 10) + ll_sched_clock();
}
/* in poll/select we use the global sysctl_net_ll_poll value */
/* in poll/select we use the global sysctl_net_ll_poll value
* only call sched_clock() if enabled
*/
static inline u64 ll_end_time(void)
{
return ((u64)ACCESS_ONCE(sysctl_net_ll_poll) << 10) + ll_sched_clock();
u64 end_time = ACCESS_ONCE(sysctl_net_ll_poll);
return end_time ? (end_time << 10) + ll_sched_clock() : 0;
}
static inline bool sk_valid_ll(struct sock *sk)
@@ -141,6 +150,10 @@ 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)
{
return 0;
}
static inline u64 sk_ll_end_time(struct sock *sk)
{