diff options
| author | Li Chen <chenl311@chinatelecom.cn> | 2025-07-10 18:57:10 +0800 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2025-07-14 10:59:34 +0200 |
| commit | f79c9aa446d638190578515afcd06d6c9d72da55 (patch) | |
| tree | 09eed9b95b956ac3afa6289ea3b32be48f183a24 | |
| parent | fbc2010d92e595dc13d8048db2419f963c8cb25e (diff) | |
x86/smpboot: avoid SMT domain attach/destroy if SMT is not enabled
Currently, the SMT domain is added into sched_domain_topology by default.
If cpu_attach_domain() finds that the CPU SMT domain’s cpumask_weight
is just 1, it will destroy it.
On a large machine, such as one with 512 cores, this results in
512 redundant domain attach/destroy operations.
Avoid these unnecessary operations by simply checking
cpu_smt_num_threads and skip SMT domain if the SMT domain is not
enabled.
Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250710105715.66594-5-me@linux.beauty
| -rw-r--r-- | arch/x86/kernel/smpboot.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index 8038286454cf..412c813cd268 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -492,6 +492,8 @@ static struct sched_domain_topology_level x86_topology[] = { static void __init build_sched_topology(void) { + struct sched_domain_topology_level *topology = x86_topology; + /* * When there is NUMA topology inside the package invalidate the * PKG domain since the NUMA domains will auto-magically create the @@ -502,7 +504,15 @@ static void __init build_sched_topology(void) memset(&x86_topology[pkgdom], 0, sizeof(x86_topology[pkgdom])); } - set_sched_topology(x86_topology); + + /* + * Drop the SMT domains if there is only one thread per-core + * since it'll get degenerated by the scheduler anyways. + */ + if (cpu_smt_num_threads <= 1) + ++topology; + + set_sched_topology(topology); } void set_cpu_sibling_map(int cpu) |