diff options
| author | Andrea Righi <arighi@nvidia.com> | 2026-01-26 10:59:02 +0100 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2026-02-03 12:04:17 +0100 |
| commit | cd959a3562050d1c676be37f1d256a96cb067868 (patch) | |
| tree | 3aab1465ef1189b072d19ce83d5ab51f25ab0322 /kernel/sched/sched.h | |
| parent | 68ec89d0e99156803bdea3c986c0198624e40ea2 (diff) | |
sched_ext: Add a DL server for sched_ext tasks
sched_ext currently suffers starvation due to RT. The same workload when
converted to EXT can get zero runtime if RT is 100% running, causing EXT
processes to stall. Fix it by adding a DL server for EXT.
A kselftest is also included later to confirm that both DL servers are
functioning correctly:
# ./runner -t rt_stall
===== START =====
TEST: rt_stall
DESCRIPTION: Verify that RT tasks cannot stall SCHED_EXT tasks
OUTPUT:
TAP version 13
1..1
# Runtime of FAIR task (PID 1511) is 0.250000 seconds
# Runtime of RT task (PID 1512) is 4.750000 seconds
# FAIR task got 5.00% of total runtime
ok 1 PASS: FAIR task got more than 4.00% of runtime
TAP version 13
1..1
# Runtime of EXT task (PID 1514) is 0.250000 seconds
# Runtime of RT task (PID 1515) is 4.750000 seconds
# EXT task got 5.00% of total runtime
ok 2 PASS: EXT task got more than 4.00% of runtime
TAP version 13
1..1
# Runtime of FAIR task (PID 1517) is 0.250000 seconds
# Runtime of RT task (PID 1518) is 4.750000 seconds
# FAIR task got 5.00% of total runtime
ok 3 PASS: FAIR task got more than 4.00% of runtime
TAP version 13
1..1
# Runtime of EXT task (PID 1521) is 0.250000 seconds
# Runtime of RT task (PID 1522) is 4.750000 seconds
# EXT task got 5.00% of total runtime
ok 4 PASS: EXT task got more than 4.00% of runtime
ok 1 rt_stall #
===== END =====
Co-developed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Tested-by: Christian Loehle <christian.loehle@arm.com>
Link: https://patch.msgid.link/20260126100050.3854740-5-arighi@nvidia.com
Diffstat (limited to 'kernel/sched/sched.h')
| -rw-r--r-- | kernel/sched/sched.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 309101c90239..2aa4251c1520 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -414,6 +414,7 @@ extern void dl_server_init(struct sched_dl_entity *dl_se, struct rq *rq, extern void sched_init_dl_servers(void); extern void fair_server_init(struct rq *rq); +extern void ext_server_init(struct rq *rq); extern void __dl_server_attach_root(struct sched_dl_entity *dl_se, struct rq *rq); extern int dl_server_apply_params(struct sched_dl_entity *dl_se, u64 runtime, u64 period, bool init); @@ -1171,6 +1172,7 @@ struct rq { struct dl_rq dl; #ifdef CONFIG_SCHED_CLASS_EXT struct scx_rq scx; + struct sched_dl_entity ext_server; #endif struct sched_dl_entity fair_server; |