[PATCH v3 net-next 1/4] net: convert low latency sockets to sched_clock()
From: Eliezer Tamir <hidden>
Date: 2013-06-13 14:46:35
Also in:
lkml
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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 <redacted> --- include/net/ll_poll.h | 23 +++++++++++------------ net/Kconfig | 1 - 2 files changed, 11 insertions(+), 13 deletions(-)
diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
index bc262f8..c75a611 100644
--- a/include/net/ll_poll.h
+++ b/include/net/ll_poll.h@@ -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
@@ -41,11 +37,14 @@ extern unsigned long sysctl_net_ll_poll __read_mostly; #define LL_FLUSH_BUSY -2 /* we don't mind a ~2.5% imprecision */ -#define TSC_MHZ (tsc_khz >> 10) +#define USECS_TO_NS(us) (us << 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 TSC_MHZ * ACCESS_ONCE(sysctl_net_ll_poll) + get_cycles(); + return sched_clock() + USECS_TO_NS(ACCESS_ONCE(sysctl_net_ll_poll)); } static inline bool sk_valid_ll(struct sock *sk)
@@ -54,16 +53,16 @@ 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(), + return !time_after((unsigned long)sched_clock(), (unsigned long)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;
@@ -116,7 +115,7 @@ 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; }
@@ -139,7 +138,7 @@ 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; }
diff --git a/net/Kconfig b/net/Kconfig
index d6a9ce6..e591668 100644
--- a/net/Kconfig
+++ b/net/Kconfig@@ -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. ------------------------------------------------------------------------------
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