Messages in this thread Patch in this message | | | From | Vincent Guittot <> | Subject | [RFC PATCH 3/4] sched/topology: remove smt_gain | Date | Wed, 29 Aug 2018 15:19:11 +0200 |
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smt_gain is used to compute the capacity of CPUs of a SMT core with the constraint 1 < smt_gain < 2 in order to be able to compute number of CPUs per core. The field has_free_capacity of struct numa_stat, which was the last user of this computation of number of CPUs per core, has been removed by :
commit 2d4056fafa19 ("sched/numa: Remove numa_has_capacity()")
We can now remove this constraint on core capacity and use the defautl value SCHED_CAPACITY_SCALE for SMT CPUs. With this remove, SCHED_CAPACITY_SCALE becomes the maximum compute capacity of CPUs on every systems. This should help to simplify some code and remove fields like rd->max_cpu_capacity
Furthermore, arch_scale_cpu_capacity() is used with a NULL sd in several other places in the code when it wants the capacity of a CPUs to scale some metrics like in pelt, deadline or schedutil. In case on SMT, the value returned is not the capacity of SMT CPUs but default SCHED_CAPACITY_SCALE.
Remove the smt_gain field from sched_domain struct
Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: linux-kernel@vger.kernel.org (open list) Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> --- include/linux/sched/topology.h | 1 - kernel/sched/sched.h | 3 --- kernel/sched/topology.c | 2 -- 3 files changed, 6 deletions(-)
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 2634774..212792b 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -89,7 +89,6 @@ struct sched_domain { unsigned int newidle_idx; unsigned int wake_idx; unsigned int forkexec_idx; - unsigned int smt_gain; int nohz_idle; /* NOHZ IDLE status */ int flags; /* See SD_* */ diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4a2e8ca..b1715b8 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1758,9 +1758,6 @@ unsigned long arch_scale_freq_capacity(int cpu) static __always_inline unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu) { - if (sd && (sd->flags & SD_SHARE_CPUCAPACITY) && (sd->span_weight > 1)) - return sd->smt_gain / sd->span_weight; - return SCHED_CAPACITY_SCALE; } #endif diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 56a0fed..069c924 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1129,7 +1129,6 @@ sd_init(struct sched_domain_topology_level *tl, .last_balance = jiffies, .balance_interval = sd_weight, - .smt_gain = 0, .max_newidle_lb_cost = 0, .next_decay_max_lb_cost = jiffies, .child = child, @@ -1155,7 +1154,6 @@ sd_init(struct sched_domain_topology_level *tl, if (sd->flags & SD_SHARE_CPUCAPACITY) { sd->flags |= SD_PREFER_SIBLING; sd->imbalance_pct = 110; - sd->smt_gain = 1178; /* ~15% */ } else if (sd->flags & SD_SHARE_PKG_RESOURCES) { sd->flags |= SD_PREFER_SIBLING; -- 2.7.4
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