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Date: Fri, 16 Mar 2007 06:30:49 +0100 (MET)
From: Patrick McHardy <kaber@...sh.net>
To: davem@...emloft.net
Cc: devik@....cz, netdev@...r.kernel.org,
Patrick McHardy <kaber@...sh.net>,
shemminger@...ux-foundation.org
Subject: [NET_SCHED 01/10]: Use ktime as clocksource
[NET_SCHED]: Use ktime as clocksource
Get rid of the manual clock source selection mess and use ktime. Also
use a scalar representation, which allows to clean up pkt_sched.h a bit
more and results in less ktime_to_ns() calls in most cases.
The PSCHED_US2JIFFIE/PSCHED_JIFFIE2US macros are implemented quite
inefficient by this patch, following patches will convert all qdiscs
to hrtimers and get rid of them entirely.
Signed-off-by: Patrick McHardy <kaber@...sh.net>
---
commit e400fa6d9e7c13d675b96958a967e747148e9b70
tree 14d5c4061e84d55e5c7633ee84c9eb098adbe709
parent c10208186a58d1149805d8c64a2846d490fce2b5
author Patrick McHardy <kaber@...sh.net> Fri, 16 Mar 2007 04:44:18 +0100
committer Patrick McHardy <kaber@...sh.net> Fri, 16 Mar 2007 04:44:18 +0100
include/net/pkt_sched.h | 169 ++++-------------------------------------------
kernel/hrtimer.c | 1
net/sched/Kconfig | 56 ----------------
net/sched/sch_api.c | 77 +--------------------
net/sched/sch_hfsc.c | 31 +--------
5 files changed, 19 insertions(+), 315 deletions(-)
diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h
index f6afee7..1c12afd 100644
--- a/include/net/pkt_sched.h
+++ b/include/net/pkt_sched.h
@@ -2,6 +2,7 @@ #ifndef __NET_PKT_SCHED_H
#define __NET_PKT_SCHED_H
#include <linux/jiffies.h>
+#include <linux/ktime.h>
#include <net/sch_generic.h>
struct qdisc_walker
@@ -37,176 +38,32 @@ static inline void *qdisc_priv(struct Qd
The things are not so bad, because we may use artifical
clock evaluated by integration of network data flow
in the most critical places.
-
- Note: we do not use fastgettimeofday.
- The reason is that, when it is not the same thing as
- gettimeofday, it returns invalid timestamp, which is
- not updated, when net_bh is active.
*/
-/* General note about internal clock.
-
- Any clock source returns time intervals, measured in units
- close to 1usec. With source CONFIG_NET_SCH_CLK_GETTIMEOFDAY it is precisely
- microseconds, otherwise something close but different chosen to minimize
- arithmetic cost. Ratio usec/internal untis in form nominator/denominator
- may be read from /proc/net/psched.
- */
-
-
-#ifdef CONFIG_NET_SCH_CLK_GETTIMEOFDAY
-
-typedef struct timeval psched_time_t;
-typedef long psched_tdiff_t;
-
-#define PSCHED_GET_TIME(stamp) do_gettimeofday(&(stamp))
-#define PSCHED_US2JIFFIE(usecs) usecs_to_jiffies(usecs)
-#define PSCHED_JIFFIE2US(delay) jiffies_to_usecs(delay)
-
-#else /* !CONFIG_NET_SCH_CLK_GETTIMEOFDAY */
-
typedef u64 psched_time_t;
typedef long psched_tdiff_t;
-#ifdef CONFIG_NET_SCH_CLK_JIFFIES
-
-#if HZ < 96
-#define PSCHED_JSCALE 14
-#elif HZ >= 96 && HZ < 192
-#define PSCHED_JSCALE 13
-#elif HZ >= 192 && HZ < 384
-#define PSCHED_JSCALE 12
-#elif HZ >= 384 && HZ < 768
-#define PSCHED_JSCALE 11
-#elif HZ >= 768
-#define PSCHED_JSCALE 10
-#endif
-
-#define PSCHED_GET_TIME(stamp) ((stamp) = (get_jiffies_64()<<PSCHED_JSCALE))
-#define PSCHED_US2JIFFIE(delay) (((delay)+(1<<PSCHED_JSCALE)-1)>>PSCHED_JSCALE)
-#define PSCHED_JIFFIE2US(delay) ((delay)<<PSCHED_JSCALE)
-
-#endif /* CONFIG_NET_SCH_CLK_JIFFIES */
-#ifdef CONFIG_NET_SCH_CLK_CPU
-#include <asm/timex.h>
-
-extern psched_tdiff_t psched_clock_per_hz;
-extern int psched_clock_scale;
-extern psched_time_t psched_time_base;
-extern cycles_t psched_time_mark;
-
-#define PSCHED_GET_TIME(stamp) \
-do { \
- cycles_t cur = get_cycles(); \
- if (sizeof(cycles_t) == sizeof(u32)) { \
- if (cur <= psched_time_mark) \
- psched_time_base += 0x100000000ULL; \
- psched_time_mark = cur; \
- (stamp) = (psched_time_base + cur)>>psched_clock_scale; \
- } else { \
- (stamp) = cur>>psched_clock_scale; \
- } \
-} while (0)
-#define PSCHED_US2JIFFIE(delay) (((delay)+psched_clock_per_hz-1)/psched_clock_per_hz)
-#define PSCHED_JIFFIE2US(delay) ((delay)*psched_clock_per_hz)
-
-#endif /* CONFIG_NET_SCH_CLK_CPU */
-
-#endif /* !CONFIG_NET_SCH_CLK_GETTIMEOFDAY */
-
-#ifdef CONFIG_NET_SCH_CLK_GETTIMEOFDAY
-#define PSCHED_TDIFF(tv1, tv2) \
-({ \
- int __delta_sec = (tv1).tv_sec - (tv2).tv_sec; \
- int __delta = (tv1).tv_usec - (tv2).tv_usec; \
- if (__delta_sec) { \
- switch (__delta_sec) { \
- default: \
- __delta = 0; \
- case 2: \
- __delta += USEC_PER_SEC; \
- case 1: \
- __delta += USEC_PER_SEC; \
- } \
- } \
- __delta; \
-})
-
-static inline int
-psched_tod_diff(int delta_sec, int bound)
-{
- int delta;
-
- if (bound <= USEC_PER_SEC || delta_sec > (0x7FFFFFFF/USEC_PER_SEC)-1)
- return bound;
- delta = delta_sec * USEC_PER_SEC;
- if (delta > bound || delta < 0)
- delta = bound;
- return delta;
-}
-
-#define PSCHED_TDIFF_SAFE(tv1, tv2, bound) \
-({ \
- int __delta_sec = (tv1).tv_sec - (tv2).tv_sec; \
- int __delta = (tv1).tv_usec - (tv2).tv_usec; \
- switch (__delta_sec) { \
- default: \
- __delta = psched_tod_diff(__delta_sec, bound); break; \
- case 2: \
- __delta += USEC_PER_SEC; \
- case 1: \
- __delta += USEC_PER_SEC; \
- case 0: \
- if (__delta > bound || __delta < 0) \
- __delta = bound; \
- } \
- __delta; \
-})
-
-#define PSCHED_TLESS(tv1, tv2) (((tv1).tv_usec < (tv2).tv_usec && \
- (tv1).tv_sec <= (tv2).tv_sec) || \
- (tv1).tv_sec < (tv2).tv_sec)
-
-#define PSCHED_TADD2(tv, delta, tv_res) \
-({ \
- int __delta = (tv).tv_usec + (delta); \
- (tv_res).tv_sec = (tv).tv_sec; \
- while (__delta >= USEC_PER_SEC) { (tv_res).tv_sec++; __delta -= USEC_PER_SEC; } \
- (tv_res).tv_usec = __delta; \
-})
-
-#define PSCHED_TADD(tv, delta) \
-({ \
- (tv).tv_usec += (delta); \
- while ((tv).tv_usec >= USEC_PER_SEC) { (tv).tv_sec++; \
- (tv).tv_usec -= USEC_PER_SEC; } \
-})
-
-/* Set/check that time is in the "past perfect";
- it depends on concrete representation of system time
- */
-
-#define PSCHED_SET_PASTPERFECT(t) ((t).tv_sec = 0)
-#define PSCHED_IS_PASTPERFECT(t) ((t).tv_sec == 0)
+/* Avoid doing 64 bit divide by 1000 */
+#define PSCHED_US2NS(x) ((s64)(x) << 10)
+#define PSCHED_NS2US(x) ((x) >> 10)
-#define PSCHED_AUDIT_TDIFF(t) ({ if ((t) > 2000000) (t) = 2000000; })
+#define PSCHED_TICKS_PER_SEC PSCHED_NS2US(NSEC_PER_SEC)
+#define PSCHED_GET_TIME(stamp) \
+ ((stamp) = PSCHED_NS2US(ktime_to_ns(ktime_get())))
-#else /* !CONFIG_NET_SCH_CLK_GETTIMEOFDAY */
+#define PSCHED_US2JIFFIE(usecs) usecs_to_jiffies(PSCHED_US2NS((usecs)) / NSEC_PER_USEC)
+#define PSCHED_JIFFIE2US(delay) PSCHED_NS2US(jiffies_to_usecs((delay)) * NSEC_PER_USEC)
-#define PSCHED_TDIFF(tv1, tv2) (long)((tv1) - (tv2))
+#define PSCHED_TDIFF(tv1, tv2) (long)((tv1) - (tv2))
#define PSCHED_TDIFF_SAFE(tv1, tv2, bound) \
- min_t(long long, (tv1) - (tv2), bound)
-
-
-#define PSCHED_TLESS(tv1, tv2) ((tv1) < (tv2))
+ min_t(long long, (tv1) - (tv2), bound)
+#define PSCHED_TLESS(tv1, tv2) ((tv1) < (tv2))
#define PSCHED_TADD2(tv, delta, tv_res) ((tv_res) = (tv) + (delta))
-#define PSCHED_TADD(tv, delta) ((tv) += (delta))
+#define PSCHED_TADD(tv, delta) ((tv) += (delta))
#define PSCHED_SET_PASTPERFECT(t) ((t) = 0)
#define PSCHED_IS_PASTPERFECT(t) ((t) == 0)
#define PSCHED_AUDIT_TDIFF(t)
-#endif /* !CONFIG_NET_SCH_CLK_GETTIMEOFDAY */
-
extern struct Qdisc_ops pfifo_qdisc_ops;
extern struct Qdisc_ops bfifo_qdisc_ops;
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ec4cb9f..8eda12c 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -59,6 +59,7 @@ ktime_t ktime_get(void)
return timespec_to_ktime(now);
}
+EXPORT_SYMBOL_GPL(ktime_get);
/**
* ktime_get_real - get the real (wall-) time in ktime_t format
diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index f4544dd..475df84 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -46,62 +46,6 @@ config NET_SCH_FIFO
if NET_SCHED
-choice
- prompt "Packet scheduler clock source"
- default NET_SCH_CLK_GETTIMEOFDAY
- ---help---
- Packet schedulers need a monotonic clock that increments at a static
- rate. The kernel provides several suitable interfaces, each with
- different properties:
-
- - high resolution (us or better)
- - fast to read (minimal locking, no i/o access)
- - synchronized on all processors
- - handles cpu clock frequency changes
-
- but nothing provides all of the above.
-
-config NET_SCH_CLK_JIFFIES
- bool "Timer interrupt"
- ---help---
- Say Y here if you want to use the timer interrupt (jiffies) as clock
- source. This clock source is fast, synchronized on all processors and
- handles cpu clock frequency changes, but its resolution is too low
- for accurate shaping except at very low speed.
-
-config NET_SCH_CLK_GETTIMEOFDAY
- bool "gettimeofday"
- ---help---
- Say Y here if you want to use gettimeofday as clock source. This clock
- source has high resolution, is synchronized on all processors and
- handles cpu clock frequency changes, but it is slow.
-
- Choose this if you need a high resolution clock source but can't use
- the CPU's cycle counter.
-
-# don't allow on SMP x86 because they can have unsynchronized TSCs.
-# gettimeofday is a good alternative
-config NET_SCH_CLK_CPU
- bool "CPU cycle counter"
- depends on ((X86_TSC || X86_64) && !SMP) || ALPHA || SPARC64 || PPC64 || IA64
- ---help---
- Say Y here if you want to use the CPU's cycle counter as clock source.
- This is a cheap and high resolution clock source, but on some
- architectures it is not synchronized on all processors and doesn't
- handle cpu clock frequency changes.
-
- The useable cycle counters are:
-
- x86/x86_64 - Timestamp Counter
- alpha - Cycle Counter
- sparc64 - %ticks register
- ppc64 - Time base
- ia64 - Interval Time Counter
-
- Choose this if your CPU's cycle counter is working properly.
-
-endchoice
-
comment "Queueing/Scheduling"
config NET_SCH_CBQ
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 4a927a5..d71bf79 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -1175,15 +1175,12 @@ #endif
return -1;
}
-static int psched_us_per_tick = 1;
-static int psched_tick_per_us = 1;
-
#ifdef CONFIG_PROC_FS
static int psched_show(struct seq_file *seq, void *v)
{
seq_printf(seq, "%08x %08x %08x %08x\n",
- psched_tick_per_us, psched_us_per_tick,
- 1000000, HZ);
+ (u32)NSEC_PER_USEC, (u32)PSCHED_US2NS(1),
+ 1000000, HZ);
return 0;
}
@@ -1202,80 +1199,10 @@ static const struct file_operations psch
};
#endif
-#ifdef CONFIG_NET_SCH_CLK_CPU
-psched_tdiff_t psched_clock_per_hz;
-int psched_clock_scale;
-EXPORT_SYMBOL(psched_clock_per_hz);
-EXPORT_SYMBOL(psched_clock_scale);
-
-psched_time_t psched_time_base;
-cycles_t psched_time_mark;
-EXPORT_SYMBOL(psched_time_mark);
-EXPORT_SYMBOL(psched_time_base);
-
-/*
- * Periodically adjust psched_time_base to avoid overflow
- * with 32-bit get_cycles(). Safe up to 4GHz CPU.
- */
-static void psched_tick(unsigned long);
-static DEFINE_TIMER(psched_timer, psched_tick, 0, 0);
-
-static void psched_tick(unsigned long dummy)
-{
- if (sizeof(cycles_t) == sizeof(u32)) {
- psched_time_t dummy_stamp;
- PSCHED_GET_TIME(dummy_stamp);
- psched_timer.expires = jiffies + 1*HZ;
- add_timer(&psched_timer);
- }
-}
-
-int __init psched_calibrate_clock(void)
-{
- psched_time_t stamp, stamp1;
- struct timeval tv, tv1;
- psched_tdiff_t delay;
- long rdelay;
- unsigned long stop;
-
- psched_tick(0);
- stop = jiffies + HZ/10;
- PSCHED_GET_TIME(stamp);
- do_gettimeofday(&tv);
- while (time_before(jiffies, stop)) {
- barrier();
- cpu_relax();
- }
- PSCHED_GET_TIME(stamp1);
- do_gettimeofday(&tv1);
-
- delay = PSCHED_TDIFF(stamp1, stamp);
- rdelay = tv1.tv_usec - tv.tv_usec;
- rdelay += (tv1.tv_sec - tv.tv_sec)*1000000;
- if (rdelay > delay)
- return -1;
- delay /= rdelay;
- psched_tick_per_us = delay;
- while ((delay>>=1) != 0)
- psched_clock_scale++;
- psched_us_per_tick = 1<<psched_clock_scale;
- psched_clock_per_hz = (psched_tick_per_us*(1000000/HZ))>>psched_clock_scale;
- return 0;
-}
-#endif
-
static int __init pktsched_init(void)
{
struct rtnetlink_link *link_p;
-#ifdef CONFIG_NET_SCH_CLK_CPU
- if (psched_calibrate_clock() < 0)
- return -1;
-#elif defined(CONFIG_NET_SCH_CLK_JIFFIES)
- psched_tick_per_us = HZ<<PSCHED_JSCALE;
- psched_us_per_tick = 1000000;
-#endif
-
link_p = rtnetlink_links[PF_UNSPEC];
/* Setup rtnetlink links. It is made here to avoid
diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c
index 396deb7..09cf6e4 100644
--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -195,20 +195,6 @@ struct hfsc_sched
struct timer_list wd_timer; /* watchdog timer */
};
-/*
- * macros
- */
-#ifdef CONFIG_NET_SCH_CLK_GETTIMEOFDAY
-#include <linux/time.h>
-#undef PSCHED_GET_TIME
-#define PSCHED_GET_TIME(stamp) \
-do { \
- struct timeval tv; \
- do_gettimeofday(&tv); \
- (stamp) = 1ULL * USEC_PER_SEC * tv.tv_sec + tv.tv_usec; \
-} while (0)
-#endif
-
#define HT_INFINITY 0xffffffffffffffffULL /* infinite time value */
@@ -394,28 +380,17 @@ cftree_update(struct hfsc_class *cl)
* ism: (psched_us/byte) << ISM_SHIFT
* dx: psched_us
*
- * Clock source resolution (CONFIG_NET_SCH_CLK_*)
- * JIFFIES: for 48<=HZ<=1534 resolution is between 0.63us and 1.27us.
- * CPU: resolution is between 0.5us and 1us.
- * GETTIMEOFDAY: resolution is exactly 1us.
+ * The clock source resolution with ktime is 1.024us.
*
* sm and ism are scaled in order to keep effective digits.
* SM_SHIFT and ISM_SHIFT are selected to keep at least 4 effective
* digits in decimal using the following table.
*
- * Note: We can afford the additional accuracy (altq hfsc keeps at most
- * 3 effective digits) thanks to the fact that linux clock is bounded
- * much more tightly.
- *
* bits/sec 100Kbps 1Mbps 10Mbps 100Mbps 1Gbps
* ------------+-------------------------------------------------------
- * bytes/0.5us 6.25e-3 62.5e-3 625e-3 6250e-e 62500e-3
- * bytes/us 12.5e-3 125e-3 1250e-3 12500e-3 125000e-3
- * bytes/1.27us 15.875e-3 158.75e-3 1587.5e-3 15875e-3 158750e-3
+ * bytes/1.024us 12.8e-3 128e-3 1280e-3 12800e-3 128000e-3
*
- * 0.5us/byte 160 16 1.6 0.16 0.016
- * us/byte 80 8 0.8 0.08 0.008
- * 1.27us/byte 63 6.3 0.63 0.063 0.0063
+ * 1.024us/byte 78.125 7.8125 0.78125 0.078125 0.0078125
*/
#define SM_SHIFT 20
#define ISM_SHIFT 18
-
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