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Date: Fri, 14 Jun 2013 04:57:00 +0300
From: Eliezer Tamir <eliezer.tamir@...ux.intel.com>
To: David Miller <davem@...emloft.net>
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
Jesse Brandeburg <jesse.brandeburg@...el.com>,
Don Skidmore <donald.c.skidmore@...el.com>,
e1000-devel@...ts.sourceforge.net,
Willem de Bruijn <willemb@...gle.com>,
Eric Dumazet <erdnetdev@...il.com>,
Ben Hutchings <bhutchings@...arflare.com>,
Andi Kleen <andi@...stfloor.org>, HPA <hpa@...or.com>,
Eilon Greenstien <eilong@...adcom.com>,
Or Gerlitz <or.gerlitz@...il.com>,
Amir Vadai <amirv@...lanox.com>,
Alex Rosenbaum <alexr@...lanox.com>,
Avner Ben Hanoch <avnerb@...lanox.com>,
Or Kehati <ork@...lanox.com>, sockperf-dev@...glegroups.com,
Eliezer Tamir <eliezer@...ir.org.il>
Subject: [PATCH v4 net-next 2/4] 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@...ux.intel.com>
---
include/net/ll_poll.h | 32 +++++++++++++++++---------------
net/Kconfig | 1 -
2 files changed, 17 insertions(+), 16 deletions(-)
diff --git a/include/net/ll_poll.h b/include/net/ll_poll.h
index 44e2f70..8608547 100644
--- a/include/net/ll_poll.h
+++ b/include/net/ll_poll.h
@@ -21,10 +21,6 @@
* e1000-devel Mailing List <e1000-devel@...ts.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 +57,16 @@ 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;
@@ -117,7 +119,7 @@ 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 +142,7 @@ 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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