cregit-Linux how code gets into the kernel

Release 4.11 net/sched/sch_hfsc.c

Directory: net/sched
/*
 * Copyright (c) 2003 Patrick McHardy, <kaber@trash.net>
 *
 * 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 <olwi@aq.ml.com.ua> 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 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 {
	
struct Qdisc_class_common cl_common;
	
unsigned int	refcnt;		/* usage count */

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

	
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 */

	
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_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_cvtoff;		/* largest virtual time seen among
                                           the children */

	
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 */

	
u8		cl_flags;	/* which curves are valid */
	
u32		cl_vtperiod;	/* vt period sequence number */
	
u32		cl_parentperiod;/* parent's vt period sequence number*/
	
u32		cl_nactive;	/* number of active children */
};


struct hfsc_sched {
	
u16	defcls;				/* default class id */
	
struct hfsc_class root;			/* root class */
	
struct Qdisc_class_hash clhash;		/* class hash */
	
struct rb_root eligible;		/* eligible tree */
	
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); }

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

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

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/* 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; }

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/* 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); }

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/* * 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); }

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

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

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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; }

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/* * 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; }

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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); }

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

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

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/* * 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 and PSCHED_SHIFT 10 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 * * So, for PSCHED_SHIFT 10 we need: SM_SHIFT 20, ISM_SHIFT 18. */ #define SM_SHIFT (30 - PSCHED_SHIFT) #define ISM_SHIFT (8 + PSCHED_SHIFT) #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; }

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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; }

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/* 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; }

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/* 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; }

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/* 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; }

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/* 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; }

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/* 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; }

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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); }

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/* * 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; }

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/* * 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; }

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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; }

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/* * 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) */ y1 = rtsc_x2y(rtsc, x); if (y1 <= y) { /* rtsc is below isc, no change to rtsc */ return; } y2 = rtsc_x2y(rtsc, x + isc->dx); if (y2 >= y + isc->dy) { /* rtsc is above isc, replace rtsc by isc */ rtsc->x = x; rtsc->y = y; rtsc->dx = isc->dx; rtsc->dy = isc->dy; return; } /* * the two curves intersect * compute the offsets (dx, dy) using the reverse * function of seg_x2y() * seg_x2y(dx, sm1) == seg_x2y(dx, sm2) + (y1 - y) */ dx = (y1 - y) << SM_SHIFT; dsm = isc->sm1 - isc->sm2; do_div(dx, dsm); /* * check if (x, y1) belongs to the 1st segment of rtsc. * if so, add the offset. */ if (rtsc->x + rtsc->dx > x) dx += rtsc->x + rtsc->dx - x; dy = seg_x2y(dx, isc->sm1); rtsc->x = x; rtsc->y = y; rtsc->dx = dx; rtsc->dy = dy; }

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static void init_ed(struct hfsc_class *cl, unsigned int next_len) { u64 cur_time = psched_get_time(); /* update the deadline curve */ rtsc_min(&cl->cl_deadline, &cl->cl_rsc, cur_time, cl->cl_cumul); /* * update the eligible curve. * for concave, it is equal to the deadline curve. * for convex, it is a linear curve with slope m2. */ cl->cl_eligible = cl->cl_deadline; if (cl->cl_rsc.sm1 <= cl->cl_rsc.sm2) { cl->cl_eligible.dx = 0; cl->cl_eligible.dy = 0; } /* compute e and d */ cl->cl_e = rtsc_y2x(&cl->cl_eligible, cl->cl_cumul); cl->cl_d = rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len); eltree_insert(cl); }

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static void update_ed(struct hfsc_class *cl, unsigned int next_len) { cl->cl_e = rtsc_y2x(&cl->cl_eligible, cl->cl_cumul); cl->cl_d = rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len); eltree_update(cl); }

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static inline void update_d(struct hfsc_class *cl, unsigned int next_len) { cl->cl_d = rtsc_y2x(&cl->cl_deadline, cl->cl_cumul + next_len); }

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static inline void update_cfmin(struct hfsc_class *cl) { struct rb_node *n = rb_first(&cl->cf_tree); struct hfsc_class *p; if (n == NULL) { cl->cl_cfmin = 0; return; } p = rb_entry(n, struct hfsc_class, cf_node); cl->cl_cfmin = p->cl_f; }

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static void init_vf(struct hfsc_class *cl, unsigned int len) { struct hfsc_class *max_cl; struct rb_node *n; u64 vt, f, cur_time; int go_active; cur_time = 0; go_active = 1; for (; cl->cl_parent != NULL; cl = cl->cl_parent) { if (go_active && cl->cl_nactive++ == 0) go_active = 1; else go_active = 0; if (go_active) { n = rb_last(&cl->cl_parent->vt_tree); if (n != NULL) { max_cl = rb_entry(n, struct hfsc_class, vt_node); /* * set vt to the average of the min and max * classes. if the parent's period didn't * change, don't decrease vt of the class. */ vt = max_cl->cl_vt; if (cl->cl_parent->cl_cvtmin != 0) vt = (cl->cl_parent->cl_cvtmin + vt)/2; if (cl->cl_parent->cl_vtperiod != cl->cl_parentperiod || vt > cl->cl_vt) cl->cl_vt = vt; } else { /* * first child for a new parent backlog period. * initialize cl_vt to the highest value seen * among the siblings. this is analogous to * what cur_time would provide in realtime case. */ cl->cl_vt = cl->cl_parent->cl_cvtoff; cl->cl_parent->cl_cvtmin = 0; } /* update the virtual curve */ rtsc_min(&cl->cl_virtual, &cl->cl_fsc, cl->cl_vt, cl->cl_total); cl->cl_vtadj = 0; cl->cl_vtperiod++; /* increment vt period */ cl->cl_parentperiod = cl->cl_parent->cl_vtperiod; if (cl->cl_parent->cl_nactive == 0) cl->cl_parentperiod++; cl->cl_f = 0; vttree_insert(cl); cftree_insert(cl); if (cl->cl_flags & HFSC_USC) { /* class has upper limit curve */ if (cur_time == 0) cur_time = psched_get_time(); /* update the ulimit curve */ rtsc_min(&cl->cl_ulimit, &cl->cl_usc, cur_time, cl->cl_total); /* compute myf */ cl->cl_myf = rtsc_y2x(&cl->cl_ulimit, cl->cl_total); } } f = max(cl->cl_myf, cl->cl_cfmin); if (f != cl->cl_f) { cl->cl_f = f; cftree_update(cl); } update_cfmin(cl->cl_parent); } }

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Michal Soltys71.89%233.33%
Total370100.00%6100.00%


static void update_vf(struct hfsc_class *cl, unsigned int len, u64 cur_time) { u64 f; /* , myf_bound, delta; */ int go_passive = 0; if (cl->qdisc->q.qlen == 0 && cl->cl_flags & HFSC_FSC) go_passive = 1; for (; cl->cl_parent != NULL; cl = cl->cl_parent) { cl->cl_total += len; if (!(cl->cl_flags & HFSC_FSC) || cl->cl_nactive == 0) continue; if (go_passive && --cl->cl_nactive == 0) go_passive = 1; else go_passive = 0; /* update vt */ cl->cl_vt = rtsc_y2x(&cl->cl_virtual, cl->cl_total) + cl->cl_vtadj; /* * if vt of the class is smaller than cvtmin, * the class was skipped in the past due to non-fit. * if so, we need to adjust vtadj. */ if (cl->cl_vt < cl->cl_parent->cl_cvtmin) { cl->cl_vtadj += cl->cl_parent->cl_cvtmin - cl->cl_vt; cl->cl_vt = cl