From: Patrick McHardy Date: Fri, 16 Mar 2007 08:18:42 +0000 (-0700) Subject: [NET_SCHED]: Use ktime as clocksource X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=641b9e0e8b7f96425da6ce98f3361e3af0baee29;p=openwrt%2Fstaging%2Fblogic.git [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 Signed-off-by: David S. Miller --- diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h index f6afee73235d..1c12afd113d6 100644 --- a/include/net/pkt_sched.h +++ b/include/net/pkt_sched.h @@ -2,6 +2,7 @@ #define __NET_PKT_SCHED_H #include +#include #include struct qdisc_walker @@ -37,176 +38,32 @@ static inline void *qdisc_priv(struct Qdisc *q) 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_JIFFIE2US(delay) ((delay)< - -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 b74860aaf5f1..f5cfde8c9025 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 f4544dd86476..475df8449be9 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 4a927a5e1fa6..d71bf79eb80b 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -1175,15 +1175,12 @@ reclassify: 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 psched_fops = { }; #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; - 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< -#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