Messages in this thread |  | | Date | Sat, 12 Mar 2022 13:05:18 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH V2] sched: topology: make cache topology separate from cpu topology |
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On Thu, Mar 10, 2022 at 07:25:33PM -0800, Qing Wang wrote: > From: Wang Qing <wangqing@vivo.com> > > Some architectures(e.g. ARM64), caches are implemented like below: > SD(Level 1): ************ DIE ************ > SD(Level 0): **** MC **** **** MC ***** > cluster: **cluster 0** **cluster 1** > cores: 0 1 2 3 4 5 6 7 > cache(Level 1): C C C C C C C C > cache(Level 2): **C** **C** **C** **C** > cache(Level 3): *******shared Level 3******** > sd_llc_id(current): 0 0 0 0 4 4 4 4 > sd_llc_id(should be): 0 0 2 2 4 4 6 6 > > Caches and cpus have different topology, this causes cpus_share_cache() > return the wrong value in sd, which will affect the CPU load balance.
Then fix your SD_flags already.
> diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h > index cce6136b..3048fa6 > --- a/include/linux/arch_topology.h > +++ b/include/linux/arch_topology.h > @@ -82,6 +82,8 @@ extern struct cpu_topology cpu_topology[NR_CPUS]; > #define topology_cluster_cpumask(cpu) (&cpu_topology[cpu].cluster_sibling) > #define topology_llc_cpumask(cpu) (&cpu_topology[cpu].llc_sibling) > void init_cpu_topology(void); > +void init_cpu_cache_topology(void); > +void fix_cpu_llc(int cpu, int *first_cpu, int *cpu_num); > void store_cpu_topology(unsigned int cpuid); > const struct cpumask *cpu_coregroup_mask(int cpu); > const struct cpumask *cpu_clustergroup_mask(int cpu); > diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c > index d201a70..d894ced > --- a/kernel/sched/topology.c > +++ b/kernel/sched/topology.c > @@ -661,6 +661,9 @@ static void update_top_cache_domain(int cpu) > if (sd) { > id = cpumask_first(sched_domain_span(sd)); > size = cpumask_weight(sched_domain_span(sd)); > +#ifdef CONFIG_GENERIC_ARCH_TOPOLOGY > + fix_cpu_llc(cpu, &id, &size); > +#endif > sds = sd->shared; > }
NAK on that.
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