sch_hfsc.c

linux 内核源代码

/*
 * Copyright (c) 2003 Patrick McHardy, <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * 2003-10-17 - Ported from altq
 */
/*
 * Copyright (c) 1997-1999 Carnegie Mellon University. All Rights Reserved.
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation is hereby granted (including for commercial or
 * for-profit use), provided that both the copyright notice and this
 * permission notice appear in all copies of the software, derivative
 * works, or modified versions, and any portions thereof.
 *
 * THIS SOFTWARE IS EXPERIMENTAL AND IS KNOWN TO HAVE BUGS, SOME OF
 * WHICH MAY HAVE SERIOUS CONSEQUENCES.  CARNEGIE MELLON PROVIDES THIS
 * SOFTWARE IN ITS ``AS IS'' CONDITION, AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 *
 * Carnegie Mellon encourages (but does not require) users of this
 * software to return any improvements or extensions that they make,
 * and to grant Carnegie Mellon the rights to redistribute these
 * changes without encumbrance.
 */
/*
 * H-FSC is described in Proceedings of SIGCOMM'97,
 * "A Hierarchical Fair Service Curve Algorithm for Link-Sharing,
 * Real-Time and Priority Service"
 * by Ion Stoica, Hui Zhang, and T. S. Eugene Ng.
 *
 * Oleg Cherevko <[e-mail]> added the upperlimit for link-sharing.
 * when a class has an upperlimit, the fit-time is computed from the
 * upperlimit service curve.  the link-sharing scheduler does not schedule
 * a class whose fit-time exceeds the current time.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/compiler.h>
#include <linux/spinlock.h>
#include <linux/skbuff.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/init.h>
#include <linux/rtnetlink.h>
#include <linux/pkt_sched.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <asm/div64.h>

/*
 * kernel internal service curve representation:
 *   coordinates are given by 64 bit unsigned integers.
 *   x-axis: unit is clock count.
 *   y-axis: unit is byte.
 *
 *   The service curve parameters are converted to the internal
 *   representation. The slope values are scaled to avoid overflow.
 *   the inverse slope values as well as the y-projection of the 1st
 *   segment are kept in order to to avoid 64-bit divide operations
 *   that are expensive on 32-bit architectures.
 */

struct internal_sc
{
	u64	sm1;	/* scaled slope of the 1st segment */
	u64	ism1;	/* scaled inverse-slope of the 1st segment */
	u64	dx;	/* the x-projection of the 1st segment */
	u64	dy;	/* the y-projection of the 1st segment */
	u64	sm2;	/* scaled slope of the 2nd segment */
	u64	ism2;	/* scaled inverse-slope of the 2nd segment */
};

/* runtime service curve */
struct runtime_sc
{
	u64	x;	/* current starting position on x-axis */
	u64	y;	/* current starting position on y-axis */
	u64	sm1;	/* scaled slope of the 1st segment */
	u64	ism1;	/* scaled inverse-slope of the 1st segment */
	u64	dx;	/* the x-projection of the 1st segment */
	u64	dy;	/* the y-projection of the 1st segment */
	u64	sm2;	/* scaled slope of the 2nd segment */
	u64	ism2;	/* scaled inverse-slope of the 2nd segment */
};

enum hfsc_class_flags
{
	HFSC_RSC = 0x1,
	HFSC_FSC = 0x2,
	HFSC_USC = 0x4
};

struct hfsc_class
{
	u32		classid;	/* class id */
	unsigned int	refcnt;		/* usage count */

	struct gnet_stats_basic bstats;
	struct gnet_stats_queue qstats;
	struct gnet_stats_rate_est rate_est;
	unsigned int	level;		/* class level in hierarchy */
	struct tcf_proto *filter_list;	/* filter list */
	unsigned int	filter_cnt;	/* filter count */

	struct hfsc_sched *sched;	/* scheduler data */
	struct hfsc_class *cl_parent;	/* parent class */
	struct list_head siblings;	/* sibling classes */
	struct list_head children;	/* child classes */
	struct Qdisc	*qdisc;		/* leaf qdisc */

	struct rb_node el_node;		/* qdisc's eligible tree member */
	struct rb_root vt_tree;		/* active children sorted by cl_vt */
	struct rb_node vt_node;		/* parent's vt_tree member */
	struct rb_root cf_tree;		/* active children sorted by cl_f */
	struct rb_node cf_node;		/* parent's cf_heap member */
	struct list_head hlist;		/* hash list member */
	struct list_head dlist;		/* drop list member */

	u64	cl_total;		/* total work in bytes */
	u64	cl_cumul;		/* cumulative work in bytes done by
					   real-time criteria */

	u64 	cl_d;			/* deadline*/
	u64 	cl_e;			/* eligible time */
	u64	cl_vt;			/* virtual time */
	u64	cl_f;			/* time when this class will fit for
					   link-sharing, max(myf, cfmin) */
	u64	cl_myf;			/* my fit-time (calculated from this
					   class's own upperlimit curve) */
	u64	cl_myfadj;		/* my fit-time adjustment (to cancel
					   history dependence) */
	u64	cl_cfmin;		/* earliest children's fit-time (used
					   with cl_myf to obtain cl_f) */
	u64	cl_cvtmin;		/* minimal virtual time among the
					   children fit for link-sharing
					   (monotonic within a period) */
	u64	cl_vtadj;		/* intra-period cumulative vt
					   adjustment */
	u64	cl_vtoff;		/* inter-period cumulative vt offset */
	u64	cl_cvtmax;		/* max child's vt in the last period */
	u64	cl_cvtoff;		/* cumulative cvtmax of all periods */
	u64	cl_pcvtoff;		/* parent's cvtoff at initialization
					   time */

	struct internal_sc cl_rsc;	/* internal real-time service curve */
	struct internal_sc cl_fsc;	/* internal fair service curve */
	struct internal_sc cl_usc;	/* internal upperlimit service curve */
	struct runtime_sc cl_deadline;	/* deadline curve */
	struct runtime_sc cl_eligible;	/* eligible curve */
	struct runtime_sc cl_virtual;	/* virtual curve */
	struct runtime_sc cl_ulimit;	/* upperlimit curve */

	unsigned long	cl_flags;	/* which curves are valid */
	unsigned long	cl_vtperiod;	/* vt period sequence number */
	unsigned long	cl_parentperiod;/* parent's vt period sequence number*/
	unsigned long	cl_nactive;	/* number of active children */
};

#define HFSC_HSIZE	16

struct hfsc_sched
{
	u16	defcls;				/* default class id */
	struct hfsc_class root;			/* root class */
	struct list_head clhash[HFSC_HSIZE];	/* class hash */
	struct rb_root eligible;		/* eligible tree */
	struct list_head droplist;		/* active leaf class list (for
						   dropping) */
	struct sk_buff_head requeue;		/* requeued packet */
	struct qdisc_watchdog watchdog;		/* watchdog timer */
};

#define	HT_INFINITY	0xffffffffffffffffULL	/* infinite time value */


/*
 * eligible tree holds backlogged classes being sorted by their eligible times.
 * there is one eligible tree per hfsc instance.
 */

static void
eltree_insert(struct hfsc_class *cl)
{
	struct rb_node **p = &cl->sched->eligible.rb_node;
	struct rb_node *parent = NULL;
	struct hfsc_class *cl1;

	while (*p != NULL) {
		parent = *p;
		cl1 = rb_entry(parent, struct hfsc_class, el_node);
		if (cl->cl_e >= cl1->cl_e)
			p = &parent->rb_right;
		else
			p = &parent->rb_left;
	}
	rb_link_node(&cl->el_node, parent, p);
	rb_insert_color(&cl->el_node, &cl->sched->eligible);
}

static inline void
eltree_remove(struct hfsc_class *cl)
{
	rb_erase(&cl->el_node, &cl->sched->eligible);
}

static inline void
eltree_update(struct hfsc_class *cl)
{
	eltree_remove(cl);
	eltree_insert(cl);
}

/* find the class with the minimum deadline among the eligible classes */
static inline struct hfsc_class *
eltree_get_mindl(struct hfsc_sched *q, u64 cur_time)
{
	struct hfsc_class *p, *cl = NULL;
	struct rb_node *n;

	for (n = rb_first(&q->eligible); n != NULL; n = rb_next(n)) {
		p = rb_entry(n, struct hfsc_class, el_node);
		if (p->cl_e > cur_time)
			break;
		if (cl == NULL || p->cl_d < cl->cl_d)
			cl = p;
	}
	return cl;
}

/* find the class with minimum eligible time among the eligible classes */
static inline struct hfsc_class *
eltree_get_minel(struct hfsc_sched *q)
{
	struct rb_node *n;

	n = rb_first(&q->eligible);
	if (n == NULL)
		return NULL;
	return rb_entry(n, struct hfsc_class, el_node);
}

/*
 * vttree holds holds backlogged child classes being sorted by their virtual
 * time. each intermediate class has one vttree.
 */
static void
vttree_insert(struct hfsc_class *cl)
{
	struct rb_node **p = &cl->cl_parent->vt_tree.rb_node;
	struct rb_node *parent = NULL;
	struct hfsc_class *cl1;

	while (*p != NULL) {
		parent = *p;
		cl1 = rb_entry(parent, struct hfsc_class, vt_node);
		if (cl->cl_vt >= cl1->cl_vt)
			p = &parent->rb_right;
		else
			p = &parent->rb_left;
	}
	rb_link_node(&cl->vt_node, parent, p);
	rb_insert_color(&cl->vt_node, &cl->cl_parent->vt_tree);
}

static inline void
vttree_remove(struct hfsc_class *cl)
{
	rb_erase(&cl->vt_node, &cl->cl_parent->vt_tree);
}

static inline void
vttree_update(struct hfsc_class *cl)
{
	vttree_remove(cl);
	vttree_insert(cl);
}

static inline struct hfsc_class *
vttree_firstfit(struct hfsc_class *cl, u64 cur_time)
{
	struct hfsc_class *p;
	struct rb_node *n;

	for (n = rb_first(&cl->vt_tree); n != NULL; n = rb_next(n)) {
		p = rb_entry(n, struct hfsc_class, vt_node);
		if (p->cl_f <= cur_time)
			return p;
	}
	return NULL;
}

/*
 * get the leaf class with the minimum vt in the hierarchy
 */
static struct hfsc_class *
vttree_get_minvt(struct hfsc_class *cl, u64 cur_time)
{
	/* if root-class's cfmin is bigger than cur_time nothing to do */
	if (cl->cl_cfmin > cur_time)
		return NULL;

	while (cl->level > 0) {
		cl = vttree_firstfit(cl, cur_time);
		if (cl == NULL)
			return NULL;
		/*
		 * update parent's cl_cvtmin.
		 */
		if (cl->cl_parent->cl_cvtmin < cl->cl_vt)
			cl->cl_parent->cl_cvtmin = cl->cl_vt;
	}
	return cl;
}

static void
cftree_insert(struct hfsc_class *cl)
{
	struct rb_node **p = &cl->cl_parent->cf_tree.rb_node;
	struct rb_node *parent = NULL;
	struct hfsc_class *cl1;

	while (*p != NULL) {
		parent = *p;
		cl1 = rb_entry(parent, struct hfsc_class, cf_node);
		if (cl->cl_f >= cl1->cl_f)
			p = &parent->rb_right;
		else
			p = &parent->rb_left;
	}
	rb_link_node(&cl->cf_node, parent, p);
	rb_insert_color(&cl->cf_node, &cl->cl_parent->cf_tree);
}

static inline void
cftree_remove(struct hfsc_class *cl)
{
	rb_erase(&cl->cf_node, &cl->cl_parent->cf_tree);
}

static inline void
cftree_update(struct hfsc_class *cl)
{
	cftree_remove(cl);
	cftree_insert(cl);
}

/*
 * service curve support functions
 *
 *  external service curve parameters
 *	m: bps
 *	d: us
 *  internal service curve parameters
 *	sm: (bytes/psched_us) << SM_SHIFT
 *	ism: (psched_us/byte) << ISM_SHIFT
 *	dx: psched_us
 *
 * 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.
 *
 *  bits/sec      100Kbps     1Mbps     10Mbps     100Mbps    1Gbps
 *  ------------+-------------------------------------------------------
 *  bytes/1.024us 12.8e-3    128e-3     1280e-3    12800e-3   128000e-3
 *
 *  1.024us/byte  78.125     7.8125     0.78125    0.078125   0.0078125
 */
#define	SM_SHIFT	20
#define	ISM_SHIFT	18

#define	SM_MASK		((1ULL << SM_SHIFT) - 1)
#define	ISM_MASK	((1ULL << ISM_SHIFT) - 1)

static inline u64
seg_x2y(u64 x, u64 sm)
{
	u64 y;

	/*
	 * compute
	 *	y = x * sm >> SM_SHIFT
	 * but divide it for the upper and lower bits to avoid overflow
	 */
	y = (x >> SM_SHIFT) * sm + (((x & SM_MASK) * sm) >> SM_SHIFT);
	return y;
}

static inline u64
seg_y2x(u64 y, u64 ism)
{
	u64 x;

	if (y == 0)
		x = 0;
	else if (ism == HT_INFINITY)
		x = HT_INFINITY;
	else {
		x = (y >> ISM_SHIFT) * ism
		    + (((y & ISM_MASK) * ism) >> ISM_SHIFT);
	}
	return x;
}

/* Convert m (bps) into sm (bytes/psched us) */
static u64
m2sm(u32 m)
{
	u64 sm;

	sm = ((u64)m << SM_SHIFT);
	sm += PSCHED_TICKS_PER_SEC - 1;
	do_div(sm, PSCHED_TICKS_PER_SEC);
	return sm;
}

/* convert m (bps) into ism (psched us/byte) */
static u64
m2ism(u32 m)
{
	u64 ism;

	if (m == 0)
		ism = HT_INFINITY;
	else {
		ism = ((u64)PSCHED_TICKS_PER_SEC << ISM_SHIFT);
		ism += m - 1;
		do_div(ism, m);
	}
	return ism;
}

/* convert d (us) into dx (psched us) */
static u64
d2dx(u32 d)
{
	u64 dx;

	dx = ((u64)d * PSCHED_TICKS_PER_SEC);
	dx += USEC_PER_SEC - 1;
	do_div(dx, USEC_PER_SEC);
	return dx;
}

/* convert sm (bytes/psched us) into m (bps) */
static u32
sm2m(u64 sm)
{
	u64 m;

	m = (sm * PSCHED_TICKS_PER_SEC) >> SM_SHIFT;
	return (u32)m;
}

/* convert dx (psched us) into d (us) */
static u32
dx2d(u64 dx)
{
	u64 d;

	d = dx * USEC_PER_SEC;
	do_div(d, PSCHED_TICKS_PER_SEC);
	return (u32)d;
}

static void
sc2isc(struct tc_service_curve *sc, struct internal_sc *isc)
{
	isc->sm1  = m2sm(sc->m1);
	isc->ism1 = m2ism(sc->m1);
	isc->dx   = d2dx(sc->d);
	isc->dy   = seg_x2y(isc->dx, isc->sm1);
	isc->sm2  = m2sm(sc->m2);
	isc->ism2 = m2ism(sc->m2);
}

/*
 * initialize the runtime service curve with the given internal
 * service curve starting at (x, y).
 */
static void
rtsc_init(struct runtime_sc *rtsc, struct internal_sc *isc, u64 x, u64 y)
{
	rtsc->x	   = x;
	rtsc->y    = y;
	rtsc->sm1  = isc->sm1;
	rtsc->ism1 = isc->ism1;
	rtsc->dx   = isc->dx;
	rtsc->dy   = isc->dy;
	rtsc->sm2  = isc->sm2;
	rtsc->ism2 = isc->ism2;
}

/*
 * calculate the y-projection of the runtime service curve by the
 * given x-projection value
 */
static u64
rtsc_y2x(struct runtime_sc *rtsc, u64 y)
{
	u64 x;

	if (y < rtsc->y)
		x = rtsc->x;
	else if (y <= rtsc->y + rtsc->dy) {
		/* x belongs to the 1st segment */
		if (rtsc->dy == 0)
			x = rtsc->x + rtsc->dx;
		else
			x = rtsc->x + seg_y2x(y - rtsc->y, rtsc->ism1);
	} else {
		/* x belongs to the 2nd segment */
		x = rtsc->x + rtsc->dx
		    + seg_y2x(y - rtsc->y - rtsc->dy, rtsc->ism2);
	}
	return x;
}

static u64
rtsc_x2y(struct runtime_sc *rtsc, u64 x)
{
	u64 y;

	if (x <= rtsc->x)
		y = rtsc->y;
	else if (x <= rtsc->x + rtsc->dx)
		/* y belongs to the 1st segment */
		y = rtsc->y + seg_x2y(x - rtsc->x, rtsc->sm1);
	else
		/* y belongs to the 2nd segment */
		y = rtsc->y + rtsc->dy
		    + seg_x2y(x - rtsc->x - rtsc->dx, rtsc->sm2);
	return y;
}

/*
 * update the runtime service curve by taking the minimum of the current
 * runtime service curve and the service curve starting at (x, y).
 */
static void
rtsc_min(struct runtime_sc *rtsc, struct internal_sc *isc, u64 x, u64 y)
{
	u64 y1, y2, dx, dy;
	u32 dsm;

	if (isc->sm1 <= isc->sm2) {
		/* service curve is convex */
		y1 = rtsc_x2y(rtsc, x);
		if (y1 < y)
			/* the current rtsc is smaller */
			return;
		rtsc->x = x;
		rtsc->y = y;
		return;
	}

	/*
	 * service curve is concave
	 * compute the two y values of the current rtsc
	 *	y1: at x
	 *	y2: at (x + dx)