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| author |   Tim Chen <tim.c.chen@linux.intel.com> | 2021-09-24 20:51:04 +1200 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2021-10-15 11:25:16 +0200 |
| commit | 66558b730f2533cc2bf2b74d51f5f80b81e2bad0 (patch) | |
| tree | ce653b4f61e022621c7affef860d50cad17aa218 /arch/x86/include/asm/topology.h | |
| parent | sched: Add cluster scheduler level in core and related Kconfig for ARM64 (diff) | |
| download | linux-dev-66558b730f2533cc2bf2b74d51f5f80b81e2bad0.tar.xz linux-dev-66558b730f2533cc2bf2b74d51f5f80b81e2bad0.zip | |
sched: Add cluster scheduler level for x86
There are x86 CPU architectures (e.g. Jacobsville) where L2 cahce is
shared among a cluster of cores instead of being exclusive to one
single core.
To prevent oversubscription of L2 cache, load should be balanced
between such L2 clusters, especially for tasks with no shared data.
On benchmark such as SPECrate mcf test, this change provides a boost
to performance especially on medium load system on Jacobsville. on a
Jacobsville that has 24 Atom cores, arranged into 6 clusters of 4
cores each, the benchmark number is as follow:
Improvement over baseline kernel for mcf_r
copies run time base rate
1 -0.1% -0.2%
6 25.1% 25.1%
12 18.8% 19.0%
24 0.3% 0.3%
So this looks pretty good. In terms of the system's task distribution,
some pretty bad clumping can be seen for the vanilla kernel without
the L2 cluster domain for the 6 and 12 copies case. With the extra
domain for cluster, the load does get evened out between the clusters.
Note this patch isn't an universal win as spreading isn't necessarily
a win, particually for those workload who can benefit from packing.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210924085104.44806-4-21cnbao@gmail.com
Diffstat (limited to 'arch/x86/include/asm/topology.h')
| -rw-r--r-- | arch/x86/include/asm/topology.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 9239399e5491..cc164777e661 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -103,6 +103,7 @@ static inline void setup_node_to_cpumask_map(void) { } #include <asm-generic/topology.h> extern const struct cpumask *cpu_coregroup_mask(int cpu); +extern const struct cpumask *cpu_clustergroup_mask(int cpu); #define topology_logical_package_id(cpu) (cpu_data(cpu).logical_proc_id) #define topology_physical_package_id(cpu) (cpu_data(cpu).phys_proc_id) @@ -113,7 +114,9 @@ extern const struct cpumask *cpu_coregroup_mask(int cpu); extern unsigned int __max_die_per_package; #ifdef CONFIG_SMP +#define topology_cluster_id(cpu) (per_cpu(cpu_l2c_id, cpu)) #define topology_die_cpumask(cpu) (per_cpu(cpu_die_map, cpu)) +#define topology_cluster_cpumask(cpu) (cpu_clustergroup_mask(cpu)) #define topology_core_cpumask(cpu) (per_cpu(cpu_core_map, cpu)) #define topology_sibling_cpumask(cpu) (per_cpu(cpu_sibling_map, cpu)) |