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authorPeter Zijlstra <peterz@infradead.org>2024-08-14 00:25:55 +0200
committerPeter Zijlstra <peterz@infradead.org>2024-09-03 15:26:32 +0200
commitbd9bbc96e8356886971317f57994247ca491dbf1 (patch)
treed721b1edfef1ac1bf57abab973b9ab8d91c1777a /kernel/sched/sched.h
parent436f3eed5c69c1048a5754df6e3dbb291e5cccbd (diff)
sched: Rework dl_server
When a task is selected through a dl_server, it will have p->dl_server set, such that it can account runtime to the dl_server, see update_curr_task(). Currently p->dl_server is set in pick*task() whenever it goes through the dl_server, clearing it is a bit of a mess though. The trivial solution is clearing it on the final put (now that we have this location). However, this gives a problem when: p = pick_task(rq); if (p) put_prev_set_next_task(rq, prev, next); picks the same task but through a different path, notably when it goes from picking through the dl_server to a direct pick or vice-versa. In that case we cannot readily determine wether we should clear or preserve p->dl_server. An additional complication is pick_*task() setting p->dl_server for a remote pick, it might still need to update runtime before it schedules the core_pick. Close all these holes and remove all the random clearing of p->dl_server by: - having pick_*task() manage rq->dl_server - having the final put_prev_task() clear p->dl_server - having the first set_next_task() set p->dl_server = rq->dl_server - complicate the core_sched code to save/restore rq->dl_server where appropriate. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lore.kernel.org/r/20240813224016.259853414@infradead.org
Diffstat (limited to 'kernel/sched/sched.h')
-rw-r--r--kernel/sched/sched.h14
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index aae35818cca4..2a216c9153e9 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1066,6 +1066,7 @@ struct rq {
unsigned int nr_uninterruptible;
struct task_struct __rcu *curr;
+ struct sched_dl_entity *dl_server;
struct task_struct *idle;
struct task_struct *stop;
unsigned long next_balance;
@@ -1193,6 +1194,7 @@ struct rq {
/* per rq */
struct rq *core;
struct task_struct *core_pick;
+ struct sched_dl_entity *core_dl_server;
unsigned int core_enabled;
unsigned int core_sched_seq;
struct rb_root core_tree;
@@ -2370,12 +2372,24 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next)
next->sched_class->set_next_task(rq, next, false);
}
+static inline void
+__put_prev_set_next_dl_server(struct rq *rq,
+ struct task_struct *prev,
+ struct task_struct *next)
+{
+ prev->dl_server = NULL;
+ next->dl_server = rq->dl_server;
+ rq->dl_server = NULL;
+}
+
static inline void put_prev_set_next_task(struct rq *rq,
struct task_struct *prev,
struct task_struct *next)
{
WARN_ON_ONCE(rq->curr != prev);
+ __put_prev_set_next_dl_server(rq, prev, next);
+
if (next == prev)
return;