From fac20743c7df8cc40f653fc0c901d5637a13425c Mon Sep 17 00:00:00 2001 From: Morten Rasmussen Date: Mon, 25 Jul 2016 14:34:22 +0100 Subject: [PATCH] UPSTREAM: sched/core: Introduce SD_ASYM_CPUCAPACITY sched_domain topology flag Add a topology flag to the sched_domain hierarchy indicating the lowest domain level where the full range of CPU capacities is represented by the domain members for asymmetric capacity topologies (e.g. ARM big.LITTLE). The flag is intended to indicate that extra care should be taken when placing tasks on CPUs and this level spans all the different types of CPUs found in the system (no need to look further up the domain hierarchy). This information is currently only available through iterating through the capacities of all the CPUs at parent levels in the sched_domain hierarchy. SD 2 [ 0 1 2 3] SD_ASYM_CPUCAPACITY SD 1 [ 0 1] [ 2 3] !SD_ASYM_CPUCAPACITY CPU: 0 1 2 3 capacity: 756 756 1024 1024 If the topology in the example above is duplicated to create an eight CPU example with third sched_domain level on top (SD 3), this level should not have the flag set (!SD_ASYM_CPUCAPACITY) as its two group would both have all CPU capacities represented within them. Change-Id: I1526407b90567cac387419719b7d7fdc8b259a85 Signed-off-by: Morten Rasmussen Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dietmar.eggemann@arm.com Cc: freedom.tan@mediatek.com Cc: keita.kobayashi.ym@renesas.com Cc: mgalbraith@suse.de Cc: sgurrappadi@nvidia.com Cc: vincent.guittot@linaro.org Cc: yuyang.du@intel.com Link: http://lkml.kernel.org/r/1469453670-2660-6-git-send-email-morten.rasmussen@arm.com Signed-off-by: Ingo Molnar (cherry picked from commit 1f6e6c7cb9bcd58abb5ee11243e0eefe6b36fc8e) [trivial merge conflict] Signed-off-by: Chris Redpath --- include/linux/sched.h | 1 + kernel/sched/core.c | 21 ++++++++++++++++----- 2 files changed, 17 insertions(+), 5 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index f8096788cb1b..436f36f768c6 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1003,6 +1003,7 @@ extern void wake_up_q(struct wake_q_head *head); #define SD_BALANCE_FORK 0x0008 /* Balance on fork, clone */ #define SD_BALANCE_WAKE 0x0010 /* Balance on wakeup */ #define SD_WAKE_AFFINE 0x0020 /* Wake task to waking CPU */ +#define SD_ASYM_CPUCAPACITY 0x0040 /* Groups have different max cpu capacities */ #define SD_SHARE_CPUCAPACITY 0x0080 /* Domain members share cpu capacity */ #define SD_SHARE_POWERDOMAIN 0x0100 /* Domain members share power domain */ #define SD_SHARE_PKG_RESOURCES 0x0200 /* Domain members share cpu pkg resources */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 8c5778053a20..1294c3cacab0 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6037,6 +6037,7 @@ static int sd_degenerate(struct sched_domain *sd) SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUCAPACITY | + SD_ASYM_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN | SD_SHARE_CAP_STATES)) { @@ -6068,6 +6069,7 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) SD_BALANCE_NEWIDLE | SD_BALANCE_FORK | SD_BALANCE_EXEC | + SD_ASYM_CPUCAPACITY | SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES | SD_PREFER_SIBLING | @@ -6749,11 +6751,19 @@ static int sched_domains_curr_level; /* * SD_flags allowed in topology descriptions. * - * SD_SHARE_CPUCAPACITY - describes SMT topologies - * SD_SHARE_PKG_RESOURCES - describes shared caches - * SD_NUMA - describes NUMA topologies - * SD_SHARE_POWERDOMAIN - describes shared power domain - * SD_SHARE_CAP_STATES - describes shared capacity states + * These flags are purely descriptive of the topology and do not prescribe + * behaviour. Behaviour is artificial and mapped in the below sd_init() + * function: + * + * SD_SHARE_CPUCAPACITY - describes SMT topologies + * SD_SHARE_PKG_RESOURCES - describes shared caches + * SD_NUMA - describes NUMA topologies + * SD_SHARE_POWERDOMAIN - describes shared power domain + * SD_ASYM_CPUCAPACITY - describes mixed capacity topologies + * SD_SHARE_CAP_STATES - describes shared capacity states + * + * Odd one out, which beside describing the topology has a quirk also + * prescribes the desired behaviour that goes along with it: * * Odd one out: * SD_ASYM_PACKING - describes SMT quirks @@ -6763,6 +6773,7 @@ static int sched_domains_curr_level; SD_SHARE_PKG_RESOURCES | \ SD_NUMA | \ SD_ASYM_PACKING | \ + SD_ASYM_CPUCAPACITY | \ SD_SHARE_POWERDOMAIN | \ SD_SHARE_CAP_STATES) -- 2.34.1