diff options
| 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/Kconfig | |
| parent | 778c558f49a2cb3dc7b18a80ff515e82aa813627 (diff) | |
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/Kconfig')
| -rw-r--r-- | arch/x86/Kconfig | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index ab83c22d274e..349e59b2f0e3 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1001,6 +1001,17 @@ config NR_CPUS This is purely to save memory: each supported CPU adds about 8KB to the kernel image. +config SCHED_CLUSTER + bool "Cluster scheduler support" + depends on SMP + default y + help + Cluster scheduler support improves the CPU scheduler's decision + making when dealing with machines that have clusters of CPUs. + Cluster usually means a couple of CPUs which are placed closely + by sharing mid-level caches, last-level cache tags or internal + busses. + config SCHED_SMT def_bool y if SMP |