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- Add three new functions to support circular run queues.

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- runq_add_pri allows the caller to position the thread at any rqindex
   regardless of priority.
 - runq_choose_from() chooses the lowest priority thread starting from a given
   index.  The index is updated with the rqindex of the chosen thread.  This
   routine is used to pick the lowest priority relative to a given index.
 - runq_remove_idx() updates the index if the run queue that held the removed
   thread is now empty.
This commit is contained in:
Jeff Roberson 2007-01-04 08:39:58 +00:00
parent 783af89c54
commit 3fed7d239a
2 changed files with 97 additions and 5 deletions
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97
sys/kern/kern_switch.c
View File

@ -383,6 +383,48 @@ runq_findbit(struct runq *rq)
return (-1);
}
static __inline int
runq_findbit_from(struct runq *rq, int start)
{
struct rqbits *rqb;
int bit;
int pri;
int i;
rqb = &rq->rq_status;
bit = start & (RQB_BPW -1);
pri = 0;
CTR1(KTR_RUNQ, "runq_findbit_from: start %d", start);
again:
for (i = RQB_WORD(start); i < RQB_LEN; i++) {
CTR3(KTR_RUNQ, "runq_findbit_from: bits %d = %#x bit = %d",
i, rqb->rqb_bits[i], bit);
if (rqb->rqb_bits[i]) {
if (bit != 0) {
for (pri = bit; pri < RQB_BPW; pri++)
if (rqb->rqb_bits[i] & (1ul << pri))
break;
bit = 0;
if (pri >= RQB_BPW)
continue;
} else
pri = RQB_FFS(rqb->rqb_bits[i]);
pri += (i << RQB_L2BPW);
CTR3(KTR_RUNQ, "runq_findbit_from: bits=%#x i=%d pri=%d",
rqb->rqb_bits[i], i, pri);
return (pri);
}
bit = 0;
}
if (start != 0) {
CTR0(KTR_RUNQ, "runq_findbit_from: restarting");
start = 0;
goto again;
}
return (-1);
}
/*
* Set the status bit of the queue corresponding to priority level pri,
* indicating that it is non-empty.
@ -423,6 +465,23 @@ runq_add(struct runq *rq, struct td_sched *ts, int flags)
}
}
void
runq_add_pri(struct runq *rq, struct td_sched *ts, int pri, int flags)
{
struct rqhead *rqh;
KASSERT(pri < RQ_NQS, ("runq_add_pri: %d out of range", pri));
ts->ts_rqindex = pri;
runq_setbit(rq, pri);
rqh = &rq->rq_queues[pri];
CTR5(KTR_RUNQ, "runq_add_pri: td=%p ke=%p pri=%d idx=%d rqh=%p",
ts->ts_thread, ts, ts->ts_thread->td_priority, pri, rqh);
if (flags & SRQ_PREEMPTED) {
TAILQ_INSERT_HEAD(rqh, ts, ts_procq);
} else {
TAILQ_INSERT_TAIL(rqh, ts, ts_procq);
}
}
/*
* Return true if there are runnable processes of any priority on the run
* queue, false otherwise. Has no side effects, does not modify the run
@ -496,6 +555,28 @@ runq_choose(struct runq *rq)
return (NULL);
}
struct td_sched *
runq_choose_from(struct runq *rq, int *idx)
{
struct rqhead *rqh;
struct td_sched *ts;
int pri;
mtx_assert(&sched_lock, MA_OWNED);
if ((pri = runq_findbit_from(rq, *idx)) != -1) {
rqh = &rq->rq_queues[pri];
ts = TAILQ_FIRST(rqh);
KASSERT(ts != NULL, ("runq_choose: no proc on busy queue"));
CTR4(KTR_RUNQ,
"runq_choose_from: pri=%d kse=%p idx=%d rqh=%p",
pri, ts, ts->ts_rqindex, rqh);
*idx = ts->ts_rqindex;
return (ts);
}
CTR1(KTR_RUNQ, "runq_choose_from: idleproc pri=%d", pri);
return (NULL);
}
/*
* Remove the thread from the queue specified by its priority, and clear the
* corresponding status bit if the queue becomes empty.
@ -503,21 +584,29 @@ runq_choose(struct runq *rq)
*/
void
runq_remove(struct runq *rq, struct td_sched *ts)
{
runq_remove_idx(rq, ts, NULL);
}
void
runq_remove_idx(struct runq *rq, struct td_sched *ts, int *idx)
{
struct rqhead *rqh;
int pri;
KASSERT(ts->ts_thread->td_proc->p_sflag & PS_INMEM,
("runq_remove: process swapped out"));
("runq_remove_idx: process swapped out"));
pri = ts->ts_rqindex;
rqh = &rq->rq_queues[pri];
CTR5(KTR_RUNQ, "runq_remove: td=%p, ts=%p pri=%d %d rqh=%p",
CTR5(KTR_RUNQ, "runq_remove_idx: td=%p, ts=%p pri=%d %d rqh=%p",
ts->ts_thread, ts, ts->ts_thread->td_priority, pri, rqh);
KASSERT(ts != NULL, ("runq_remove: no proc on busy queue"));
TAILQ_REMOVE(rqh, ts, ts_procq);
if (TAILQ_EMPTY(rqh)) {
CTR0(KTR_RUNQ, "runq_remove: empty");
CTR0(KTR_RUNQ, "runq_remove_idx: empty");
runq_clrbit(rq, pri);
if (idx != NULL && *idx == pri)
*idx = (pri + 1) % RQ_NQS;
}
}

5
sys/sys/runq.h
View File

@ -62,10 +62,13 @@ struct runq {
struct rqhead rq_queues[RQ_NQS];
};
void runq_add(struct runq *, struct td_sched *, int flags);
void runq_add(struct runq *, struct td_sched *, int);
void runq_add_pri(struct runq *, struct td_sched *, int, int);
int runq_check(struct runq *);
struct td_sched *runq_choose(struct runq *);
struct td_sched *runq_choose_from(struct runq *, int *);
void runq_init(struct runq *);
void runq_remove(struct runq *, struct td_sched *);
void runq_remove_idx(struct runq *, struct td_sched *, int *);
#endif