Add CPUPRI_HIGHER above the RT99 priority to denote the CPU is in use by higher priority tasks (specifically deadline).
XXX: we should probably drive PUSH-PULL from cpupri, that would automagically result in an RT-PUSH when DL sets cpupri to CPUPRI_HIGHER. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> --- kernel/sched/cpupri.c | 10 ++++++++-- kernel/sched/cpupri.h | 3 ++- kernel/sched/deadline.c | 3 +++ 3 files changed, 13 insertions(+), 3 deletions(-) --- a/kernel/sched/cpupri.c +++ b/kernel/sched/cpupri.c @@ -11,7 +11,7 @@ * This code tracks the priority of each CPU so that global migration * decisions are easy to calculate. Each CPU can be in a state as follows: * - * (INVALID), NORMAL, RT1, ... RT99 + * (INVALID), NORMAL, RT1, ... RT99, HIGHER * * going from the lowest priority to the highest. CPUs in the INVALID state * are not eligible for routing. The system maintains this state with @@ -19,7 +19,7 @@ * in that class). Therefore a typical application without affinity * restrictions can find a suitable CPU with O(1) complexity (e.g. two bit * searches). For tasks with affinity restrictions, the algorithm has a - * worst case complexity of O(min(100, nr_domcpus)), though the scenario that + * worst case complexity of O(min(101, nr_domcpus)), though the scenario that * yields the worst case search is fairly contrived. */ #include "sched.h" @@ -37,6 +37,8 @@ * 50 49 49 50 * ... * 99 0 0 99 + * + * 100 100 (CPUPRI_HIGHER) */ static int convert_prio(int prio) { @@ -54,6 +56,10 @@ static int convert_prio(int prio) case MAX_RT_PRIO-1: cpupri = CPUPRI_NORMAL; /* 0 */ break; + + case MAX_RT_PRIO: + cpupri = CPUPRI_HIGHER; /* 100 */ + break; } return cpupri; --- a/kernel/sched/cpupri.h +++ b/kernel/sched/cpupri.h @@ -1,10 +1,11 @@ /* SPDX-License-Identifier: GPL-2.0 */ -#define CPUPRI_NR_PRIORITIES MAX_RT_PRIO +#define CPUPRI_NR_PRIORITIES (MAX_RT_PRIO+1) #define CPUPRI_INVALID -1 #define CPUPRI_NORMAL 0 /* values 1-99 are for RT1-RT99 priorities */ +#define CPUPRI_HIGHER 100 struct cpupri_vec { atomic_t count; --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1364,6 +1364,8 @@ static void inc_dl_deadline(struct dl_rq if (dl_rq->earliest_dl.curr == 0 || dl_time_before(deadline, dl_rq->earliest_dl.curr)) { + if (dl_rq->earliest_dl.curr == 0) + cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_HIGHER); dl_rq->earliest_dl.curr = deadline; cpudl_set(&rq->rd->cpudl, rq->cpu, deadline); } @@ -1381,6 +1383,7 @@ static void dec_dl_deadline(struct dl_rq dl_rq->earliest_dl.curr = 0; dl_rq->earliest_dl.next = 0; cpudl_clear(&rq->rd->cpudl, rq->cpu); + cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr); } else { struct rb_node *leftmost = dl_rq->root.rb_leftmost; struct sched_dl_entity *entry;