[PATCH 07/16] sched: Make SD_BALANCE_WAKE a topology flag

Morten Rasmussen
2016-05-23T11:01:01Z

For systems with the SD_ASYM_CPUCAPACITY flag set on higher level in the
sched_domain hierarchy we need a way to enable wake-up balancing for the
lower levels as well as we may want to balance tasks that don't fit the
capacity of the previous cpu.

We have the option of introducing a new topology flag to express this
requirement, or let the existing SD_BALANCE_WAKE flag be set by the
architecture as a topology flag. The former means introducing yet
another flag, the latter breaks the current meaning of topology flags.
None of the options are really desirable.

cc: Ingo Molnar <mingo@redhat.com>
cc: Peter Zijlstra <peterz@infradead.org>

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
---
kernel/sched/core.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 558ec4a..8014b4a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5658,6 +5658,7 @@ static int sd_degenerate(struct sched_domain *sd)
SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
+ SD_BALANCE_WAKE |
SD_SHARE_CPUCAPACITY |
SD_ASYM_CPUCAPACITY |
SD_SHARE_PKG_RESOURCES |
@@ -5690,6 +5691,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
SD_BALANCE_NEWIDLE |
SD_BALANCE_FORK |
SD_BALANCE_EXEC |
+ SD_BALANCE_WAKE |
SD_ASYM_CPUCAPACITY |
SD_SHARE_CPUCAPACITY |
SD_SHARE_PKG_RESOURCES |
@@ -6308,6 +6310,7 @@ static int sched_domains_curr_level;
* Odd ones out:
* SD_ASYM_PACKING - describes SMT quirks
* SD_ASYM_CPUCAPACITY - describes mixed capacity topologies
+ * SD_BALANCE_WAKE - controls wake-up balancing (expensive)
*/
#define TOPOLOGY_SD_FLAGS \
(SD_SHARE_CPUCAPACITY | \
@@ -6315,6 +6318,7 @@ static int sched_domains_curr_level;
SD_NUMA | \
SD_ASYM_PACKING | \
SD_ASYM_CPUCAPACITY | \
+ SD_BALANCE_WAKE | \
SD_SHARE_POWERDOMAIN)

static struct sched_domain *
--
1.9.1