From: Peter Zijlstra Date: Tue, 8 Aug 2017 10:16:24 +0000 (+0200) Subject: sched/topology: Avoid pointless rebuild X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=09e0dd8e0f2e197690d34fed8cb4737114d3dd5f;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git sched/topology: Avoid pointless rebuild Fix partition_sched_domains() to try and preserve the existing machine wide domain instead of unconditionally destroying it. We do this by attempting to allocate the new single domain, only when that fails to we reuse the fallback_doms. When using fallback_doms we need to first destroy and then recreate because both the old and new could be backed by it. Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Ofer Levi(SW) Cc: Peter Zijlstra Cc: Tejun Heo Cc: Thomas Gleixner Cc: Vineet.Gupta1@synopsys.com Cc: rusty@rustcorp.com.au Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 179b90b60ec6..727daa2a0abe 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1851,7 +1851,17 @@ void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[], /* Let the architecture update CPU core mappings: */ new_topology = arch_update_cpu_topology(); - n = doms_new ? ndoms_new : 0; + if (!doms_new) { + WARN_ON_ONCE(dattr_new); + n = 0; + doms_new = alloc_sched_domains(1); + if (doms_new) { + n = 1; + cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); + } + } else { + n = ndoms_new; + } /* Destroy deleted domains: */ for (i = 0; i < ndoms_cur; i++) { @@ -1867,11 +1877,10 @@ match1: } n = ndoms_cur; - if (doms_new == NULL) { + if (!doms_new) { n = 0; doms_new = &fallback_doms; cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); - WARN_ON_ONCE(dattr_new); } /* Build new domains: */