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>

diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
index 44e2f707cb9f7a4d8df2bc0c53cb764359f8fe75..6930cbd943e214df92bab4ef2359cdf0b584ca80 100644 (file)
--- 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
 
@@ -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;
 }

diff --git a/net/Kconfig b/net/Kconfig
index d6a9ce6e18007793d4bbc7a4f5a35d2cf3abe7d4..e591668fb38fdc369045304aca69de393d3ddac6 100644 (file)
--- 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.