diff options
| author | Eliezer Tamir <eliezer.tamir@linux.intel.com> | 2013-06-28 15:59:35 +0300 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-07-01 14:06:47 -0700 |
| commit | 91e2fd337839319c7745e2cb84cfbf8cf1426a1a (patch) | |
| tree | 1a832c8fb04fc687dfd40e4a4b69b15d60049172 | |
| parent | ad6276e0fe724b1c8ac3a0bf138d151665ab2349 (diff) | |
| download | linux-91e2fd337839319c7745e2cb84cfbf8cf1426a1a.tar.bz2 | |
net: avoid calling sched_clock when LLS is off
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>
| -rw-r--r-- | fs/select.c | 11 | ||||
| -rw-r--r-- | include/net/ll_poll.h | 17 |
2 files changed, 22 insertions, 6 deletions
diff --git a/fs/select.c b/fs/select.c index 79b876eb91da..36540754bad7 100644 --- a/fs/select.c +++ b/fs/select.c @@ -402,7 +402,7 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) poll_table *wait; int retval, i, timed_out = 0; unsigned long slack = 0; - unsigned int ll_flag = POLL_LL; + unsigned int ll_flag = ll_get_flag(); u64 ll_time = ll_end_time(); rcu_read_lock(); @@ -497,7 +497,8 @@ int do_select(int n, fd_set_bits *fds, struct timespec *end_time) break; } - if (can_ll && can_poll_ll(ll_time)) + /* only if on, have sockets with POLL_LL and not out of time */ + if (ll_flag && can_ll && can_poll_ll(ll_time)) continue; /* @@ -768,7 +769,7 @@ static int do_poll(unsigned int nfds, struct poll_list *list, ktime_t expire, *to = NULL; int timed_out = 0, count = 0; unsigned long slack = 0; - unsigned int ll_flag = POLL_LL; + unsigned int ll_flag = ll_get_flag(); u64 ll_time = ll_end_time(); /* Optimise the no-wait case */ @@ -817,8 +818,10 @@ static int do_poll(unsigned int nfds, struct poll_list *list, if (count || timed_out) break; - if (can_ll && can_poll_ll(ll_time)) + /* only if on, have sockets with POLL_LL and not out of time */ + if (ll_flag && can_ll && can_poll_ll(ll_time)) continue; + /* * If this is the first loop and we have a timeout * given, then we convert to ktime_t and set the to diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h index 6d45e6f6ff4c..6c06f7c0a22d 100644 --- a/include/net/ll_poll.h +++ b/include/net/ll_poll.h @@ -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) { |