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-rw-r--r--os/port/edf.c626
1 files changed, 626 insertions, 0 deletions
diff --git a/os/port/edf.c b/os/port/edf.c
new file mode 100644
index 00000000..c406f4cc
--- /dev/null
+++ b/os/port/edf.c
@@ -0,0 +1,626 @@
+/* EDF scheduling */
+#include "u.h"
+#include "../port/lib.h"
+#include "mem.h"
+#include "dat.h"
+#include "fns.h"
+#include "../port/error.h"
+#include "../port/edf.h"
+#include <trace.h>
+
+/* debugging */
+int edfprint = 0;
+#define DPRINT if(edfprint)print
+
+static vlong now;
+extern ulong delayedscheds;
+extern Schedq runq[Nrq];
+extern int nrdy;
+extern ulong runvec;
+
+/* Statistics stuff */
+ulong nilcount;
+ulong scheds;
+vlong edfruntime;
+ulong edfnrun;
+int misseddeadlines;
+
+/* Edfschedlock protects modification of admission params */
+int edfinited;
+QLock edfschedlock;
+static Lock thelock;
+
+enum{
+ Dl, /* Invariant for schedulability test: Dl < Rl */
+ Rl,
+};
+
+static char *testschedulability(Proc*);
+static Proc *qschedulability;
+
+enum {
+ Onemicrosecond = 1000ULL,
+ Onemillisecond = 1000000ULL,
+ Onesecond = 1000000000ULL,
+ OneRound = Onemillisecond/2LL,
+ MilliRound = Onemicrosecond/2LL,
+};
+
+static int
+timeconv(Fmt *f)
+{
+ char buf[128], *sign;
+ vlong t;
+
+ buf[0] = 0;
+ switch(f->r) {
+ case 'U':
+ t = va_arg(f->args, uvlong);
+ break;
+ case 't': // vlong in nanoseconds
+ t = va_arg(f->args, vlong);
+ break;
+ default:
+ return fmtstrcpy(f, "(timeconv)");
+ }
+ if (t < 0) {
+ sign = "-";
+ t = -t;
+ }
+ else
+ sign = "";
+ if (t > Onesecond){
+ t += OneRound;
+ sprint(buf, "%s%d.%.3ds", sign, (int)(t / Onesecond), (int)(t % Onesecond)/1000000);
+ }else if (t > Onemillisecond){
+ t += MilliRound;
+ sprint(buf, "%s%d.%.3dms", sign, (int)(t / Onemillisecond), (int)(t % Onemillisecond)/1000);
+ }else if (t > Onemicrosecond)
+ sprint(buf, "%s%d.%.3dµs", sign, (int)(t / Onemicrosecond), (int)(t % Onemicrosecond));
+ else
+ sprint(buf, "%s%dns", sign, (int)t);
+ return fmtstrcpy(f, buf);
+}
+
+Edf*
+edflock(Proc *p)
+{
+ Edf *e;
+
+ if (p->edf == nil)
+ return nil;
+ ilock(&thelock);
+ if ((e = p->edf) && (e->flags & Admitted)){
+ now = todget(nil);
+ return e;
+ }
+ iunlock(&thelock);
+ return nil;
+}
+
+void
+edfunlock(void)
+{
+ edfruntime += todget(nil) - now;
+ edfnrun++;
+ iunlock(&thelock);
+}
+
+void
+edfinit(Proc*p)
+{
+ if(!edfinited){
+ fmtinstall('t', timeconv);
+ edfinited++;
+ }
+ now = todget(nil);
+ DPRINT("%t edfinit %lud[%s]\n", now, p->pid, statename[p->state]);
+ p->edf = malloc(sizeof(Edf));
+ if(p->edf == nil)
+ error(Enomem);
+ return;
+}
+
+static void
+deadlineintr(Ureg*, Timer *t)
+{
+ /* Proc reached deadline */
+ extern int panicking;
+ Proc *p;
+ void (*pt)(Proc*, int, vlong);
+
+ if(panicking || active.exiting)
+ return;
+
+ p = t->ta;
+
+ DPRINT("%t deadlineintr %lud[%s]\n", todget(nil), p->pid, statename[p->state]);
+ /* If we're interrupting something other than the proc pointed to by t->a,
+ * we've already achieved recheduling, so we need not do anything
+ * Otherwise, we must cause a reschedule, but if we call sched()
+ * here directly, the timer interrupt routine will not finish its business
+ * Instead, we cause the resched to happen when the interrupted proc
+ * returns to user space
+ */
+ if (p == up){
+ pt = proctrace;
+ if(up->trace && pt)
+ pt(up, SInts, 0);
+ up->delaysched++;
+ delayedscheds++;
+ }
+}
+
+static void
+release(Proc *p)
+{
+ /* Called with edflock held */
+ Edf *e;
+ void (*pt)(Proc*, int, vlong);
+
+ e = p->edf;
+ e->flags &= ~Yield;
+ if (e->d < now){
+ e->periods++;
+ e->r = now;
+ if ((e->flags & Sporadic) == 0){
+ /* Non sporadic processes stay true to their period;
+ * calculate next release time
+ */
+ while(e->t <= now)
+ e->t += e->T;
+ }else{
+ /* Sporadic processes may not be released earlier than
+ * one period after this release
+ */
+ e->t = e->r + e->T;
+ }
+ e->d = e->r + e->D;
+ e->S = e->C;
+ DPRINT("%t release %lud[%s], r=%t, d=%t, t=%t, S=%t\n",
+ now, p->pid, statename[p->state], e->r, e->d, e->t, e->S);
+ if (pt = proctrace){
+ pt(p, SRelease, e->r);
+ pt(p, SDeadline, e->d);
+ }
+ }else{
+ DPRINT("%t release %lud[%s], too late t=%t, called from 0x%lux\n",
+ now, p->pid, statename[p->state], e->t, getcallerpc(&p));
+ }
+}
+
+static void
+releaseintr(Ureg*, Timer *t)
+{
+ Proc *p;
+ extern int panicking;
+ Schedq *rq;
+
+ if(panicking || active.exiting)
+ return;
+
+ p = t->ta;
+ if((edflock(p)) == nil)
+ return;
+ DPRINT("%t releaseintr %lud[%s]\n", now, p->pid, statename[p->state]);
+ switch(p->state){
+ default:
+ edfunlock();
+ return;
+ case Ready:
+ /* remove proc from current runq */
+ rq = &runq[p->pri];
+ if (dequeueproc(rq, p) != p){
+ DPRINT("releaseintr: can't find proc or lock race\n");
+ release(p); /* It'll start best effort */
+ edfunlock();
+ return;
+ }
+ p->state = Waitrelease;
+ /* fall through */
+ case Waitrelease:
+ release(p);
+ edfunlock();
+ ready(p);
+ if (up){
+ up->delaysched++;
+ delayedscheds++;
+ }
+ return;
+ case Running:
+ release(p);
+ edfrun(p, 1);
+ break;
+ case Wakeme:
+ release(p);
+ edfunlock();
+ if (p->trend)
+ wakeup(p->trend);
+ p->trend = nil;
+ if (up){
+ up->delaysched++;
+ delayedscheds++;
+ }
+ return;
+ }
+ edfunlock();
+}
+
+void
+edfrecord(Proc *p)
+{
+ vlong used;
+ Edf *e;
+ void (*pt)(Proc*, int, vlong);
+
+ if((e = edflock(p)) == nil)
+ return;
+ used = now - e->s;
+ if (e->d <= now)
+ e->edfused += used;
+ else
+ e->extraused += used;
+ if (e->S > 0){
+ if (e->S <= used){
+ if(pt = proctrace)
+ pt(p, SSlice, now);
+ DPRINT("%t edfrecord slice used up\n", now);
+ e->d = now;
+ e->S = 0;
+ }else
+ e->S -= used;
+ }
+ e->s = now;
+ edfunlock();
+}
+
+void
+edfrun(Proc *p, int edfpri)
+{
+ Edf *e;
+ void (*pt)(Proc*, int, vlong);
+
+ e = p->edf;
+ /* Called with edflock held */
+ if(edfpri){
+ if (e->d <= now || e->S == 0){
+ /* Deadline reached or resources exhausted,
+ * deschedule forthwith
+ */
+ p->delaysched++;
+ delayedscheds++;
+ e->s = now;
+ return;
+ }
+ e->tns = now + e->S;
+ if (e->d < e->tns)
+ e->tns = e->d;
+ if(e->tt == nil || e->tf != deadlineintr){
+ DPRINT("%t edfrun, deadline=%t\n", now, e->tns);
+ }else{
+ DPRINT("v");
+ }
+ if(p->trace && (pt = proctrace))
+ pt(p, SInte, e->tns);
+ e->tmode = Tabsolute;
+ e->tf = deadlineintr;
+ e->ta = p;
+ timeradd(e);
+ }else{
+ DPRINT("<");
+ }
+ e->s = now;
+}
+
+char *
+edfadmit(Proc *p)
+{
+ char *err;
+ Edf *e;
+ int i;
+ Proc *r;
+ void (*pt)(Proc*, int, vlong);
+
+ e = p->edf;
+ if (e->flags & Admitted)
+ return "task state"; /* should never happen */
+
+ /* simple sanity checks */
+ if (e->T == 0)
+ return "T not set";
+ if (e->C == 0)
+ return "C not set";
+ if (e->D > e->T)
+ return "D > T";
+ if (e->D == 0) /* if D is not set, set it to T */
+ e->D = e->T;
+ if (e->C > e->D)
+ return "C > D";
+
+ qlock(&edfschedlock);
+ if (err = testschedulability(p)){
+ qunlock(&edfschedlock);
+ return err;
+ }
+ e->flags |= Admitted;
+
+ edflock(p);
+
+ if(pt = proctrace)
+ pt(p, SAdmit, now);
+
+ /* Look for another proc with the same period to synchronize to */
+ SET(r);
+ for(i=0; i<conf.nproc; i++) {
+ r = proctab(i);
+ if(r->state == Dead || r == p)
+ continue;
+ if (r->edf == nil || (r->edf->flags & Admitted) == 0)
+ continue;
+ if (r->edf->T == e->T)
+ break;
+ }
+ if (i == conf.nproc){
+ /* Can't synchronize to another proc, release now */
+ e->t = now;
+ e->d = 0;
+ release(p);
+ if (p == up){
+ DPRINT("%t edfadmit self %lud[%s], release now: r=%t d=%t t=%t\n",
+ now, p->pid, statename[p->state], e->r, e->d, e->t);
+ /* We're already running */
+ edfrun(p, 1);
+ }else{
+ /* We're releasing another proc */
+ DPRINT("%t edfadmit other %lud[%s], release now: r=%t d=%t t=%t\n",
+ now, p->pid, statename[p->state], e->r, e->d, e->t);
+ p->ta = p;
+ edfunlock();
+ qunlock(&edfschedlock);
+ releaseintr(nil, p);
+ return nil;
+ }
+ }else{
+ /* Release in synch to something else */
+ e->t = r->edf->t;
+ if (p == up){
+ DPRINT("%t edfadmit self %lud[%s], release at %t\n",
+ now, p->pid, statename[p->state], e->t);
+ edfunlock();
+ qunlock(&edfschedlock);
+ return nil;
+ }else{
+ DPRINT("%t edfadmit other %lud[%s], release at %t\n",
+ now, p->pid, statename[p->state], e->t);
+ if(e->tt == nil){
+ e->tf = releaseintr;
+ e->ta = p;
+ e->tns = e->t;
+ e->tmode = Tabsolute;
+ timeradd(e);
+ }
+ }
+ }
+ edfunlock();
+ qunlock(&edfschedlock);
+ return nil;
+}
+
+void
+edfstop(Proc *p)
+{
+ Edf *e;
+ void (*pt)(Proc*, int, vlong);
+
+ if (e = edflock(p)){
+ DPRINT("%t edfstop %lud[%s]\n", now, p->pid, statename[p->state]);
+ if(pt = proctrace)
+ pt(p, SExpel, now);
+ e->flags &= ~Admitted;
+ if (e->tt)
+ timerdel(e);
+ edfunlock();
+ }
+}
+
+static int
+yfn(void *)
+{
+ return up->trend == nil || todget(nil) >= up->edf->r;
+}
+
+void
+edfyield(void)
+{
+ /* sleep until next release */
+ Edf *e;
+ void (*pt)(Proc*, int, vlong);
+
+ if((e = edflock(up)) == nil)
+ return;
+ if(pt = proctrace)
+ pt(up, SYield, now);
+ while(e->t < now)
+ e->t += e->T;
+ e->r = e->t;
+ e->flags |= Yield;
+ e->d = now;
+ if (up->tt == nil){
+ up->tns = e->t;
+ up->tf = releaseintr;
+ up->tmode = Tabsolute;
+ up->ta = up;
+ up->trend = &up->sleep;
+ timeradd(up);
+ }else if(up->tf != releaseintr)
+ print("edfyield: surprise! 0x%lux\n", up->tf);
+ edfunlock();
+ sleep(&up->sleep, yfn, nil);
+}
+
+int
+edfready(Proc *p)
+{
+ Edf *e;
+ Schedq *rq;
+ Proc *l, *pp;
+ void (*pt)(Proc*, int, vlong);
+
+ if((e = edflock(p)) == nil)
+ return 0;
+ if (e->d <= now){
+ /* past deadline, arrange for next release */
+ if ((e->flags & Sporadic) == 0){
+ /* Non sporadic processes stay true to their period, calculate next release time */
+ while(e->t < now)
+ e->t += e->T;
+ }
+ if (now < e->t){
+ /* Next release is in the future, schedule it */
+ if (e->tt == nil || e->tf != releaseintr){
+ e->tns = e->t;
+ e->tmode = Tabsolute;
+ e->tf = releaseintr;
+ e->ta = p;
+ timeradd(e);
+ DPRINT("%t edfready %lud[%s], release=%t\n",
+ now, p->pid, statename[p->state], e->t);
+ }
+ if(p->state == Running && (e->flags & (Yield|Yieldonblock)) == 0 && (e->flags & Extratime)){
+ /* If we were running, we've overrun our CPU allocation
+ * or missed the deadline, continue running best-effort at low priority
+ * Otherwise we were blocked. If we don't yield on block, we continue
+ * best effort
+ */
+ DPRINT(">");
+ p->pri = PriExtra;
+ edfunlock();
+ return 0; /* Stick on runq[PriExtra] */
+ }
+ DPRINT("%t edfready %lud[%s] wait release at %t\n",
+ now, p->pid, statename[p->state], e->t);
+ p->state = Waitrelease;
+ edfunlock();
+ return 1; /* Make runnable later */
+ }
+ DPRINT("%t edfready %lud %s release now\n", now, p->pid, statename[p->state]);
+ /* release now */
+ release(p);
+ }
+ edfunlock();
+ DPRINT("^");
+ rq = &runq[PriEdf];
+ /* insert in queue in earliest deadline order */
+ lock(runq);
+ l = nil;
+ for(pp = rq->head; pp; pp = pp->rnext){
+ if(pp->edf->d > e->d)
+ break;
+ l = pp;
+ }
+ p->rnext = pp;
+ if (l == nil)
+ rq->head = p;
+ else
+ l->rnext = p;
+ if(pp == nil)
+ rq->tail = p;
+ rq->n++;
+ nrdy++;
+ runvec |= 1 << PriEdf;
+ p->pri = PriEdf;
+ p->readytime = m->ticks;
+ p->state = Ready;
+ unlock(runq);
+ if(pt = proctrace)
+ pt(p, SReady, now);
+ return 1;
+}
+
+
+static void
+testenq(Proc *p)
+{
+ Proc *xp, **xpp;
+ Edf *e;
+
+ e = p->edf;
+ e->testnext = nil;
+ if (qschedulability == nil) {
+ qschedulability = p;
+ return;
+ }
+ SET(xp);
+ for (xpp = &qschedulability; *xpp; xpp = &xp->edf->testnext) {
+ xp = *xpp;
+ if (e->testtime < xp->edf->testtime
+ || (e->testtime == xp->edf->testtime && e->testtype < xp->edf->testtype)){
+ e->testnext = xp;
+ *xpp = p;
+ return;
+ }
+ }
+ assert(xp->edf->testnext == nil);
+ xp->edf->testnext = p;
+}
+
+static char *
+testschedulability(Proc *theproc)
+{
+ Proc *p;
+ vlong H, G, Cb, ticks;
+ int steps, i;
+
+ /* initialize */
+ DPRINT("schedulability test %lud\n", theproc->pid);
+ qschedulability = nil;
+ for(i=0; i<conf.nproc; i++) {
+ p = proctab(i);
+ if(p->state == Dead)
+ continue;
+ if ((p->edf == nil || (p->edf->flags & Admitted) == 0) && p != theproc)
+ continue;
+ p->edf->testtype = Rl;
+ p->edf->testtime = 0;
+ DPRINT("\tInit: edfenqueue %lud\n", p->pid);
+ testenq(p);
+ }
+ H=0;
+ G=0;
+ for(steps = 0; steps < Maxsteps; steps++){
+ p = qschedulability;
+ qschedulability = p->edf->testnext;
+ ticks = p->edf->testtime;
+ switch (p->edf->testtype){
+ case Dl:
+ H += p->edf->C;
+ Cb = 0;
+ DPRINT("\tStep %3d, Ticks %t, pid %lud, deadline, H += %t → %t, Cb = %t\n",
+ steps, ticks, p->pid, p->edf->C, H, Cb);
+ if (H+Cb>ticks){
+ DPRINT("not schedulable\n");
+ return "not schedulable";
+ }
+ p->edf->testtime += p->edf->T - p->edf->D;
+ p->edf->testtype = Rl;
+ testenq(p);
+ break;
+ case Rl:
+ DPRINT("\tStep %3d, Ticks %t, pid %lud, release, G %t, C%t\n",
+ steps, ticks, p->pid, p->edf->C, G);
+ if(ticks && G <= ticks){
+ DPRINT("schedulable\n");
+ return nil;
+ }
+ G += p->edf->C;
+ p->edf->testtime += p->edf->D;
+ p->edf->testtype = Dl;
+ testenq(p);
+ break;
+ default:
+ assert(0);
+ }
+ }
+ DPRINT("probably not schedulable\n");
+ return "probably not schedulable";
+}
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