Commit-ID: 70b8301f6b8f7bc053377a9cbd0c4e42e29d9807
Gitweb: http://git.kernel.org/tip/70b8301f6b8f7bc053377a9cbd0c4e42e29d9807
Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
AuthorDate: Thu, 19 May 2016 17:09:55 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Fri, 3 Jun 2016 09:41:21 +0200
x86/topology: Add topology_max_smt_threads()
For SMT specific workarounds it is useful to know if SMT is active
on any online CPU in the system. This currently requires a loop
over all online CPUs.
Add a global variable that is updated with the maximum number
of smt threads on any CPU on online/offline, and use it for
topology_max_smt_threads()
The single call is easier to use than a loop.
Not exported to user space because user space already can use
the existing sibling interfaces to find this out.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Vince Weaver <vincent.weaver@xxxxxxxxx>
Cc: acme@xxxxxxxxxx
Cc: jolsa@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1463703002-19686-2-git-send-email-andi@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/include/asm/topology.h | 9 +++++++++
arch/x86/kernel/smpboot.c | 25 ++++++++++++++++++++++++-
2 files changed, 33 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h
index 7f991bd5..e346572 100644
--- a/arch/x86/include/asm/topology.h
+++ b/arch/x86/include/asm/topology.h
@@ -129,6 +129,14 @@ extern const struct cpumask *cpu_coregroup_mask(int cpu);
extern unsigned int __max_logical_packages;
#define topology_max_packages() (__max_logical_packages)
+
+extern int __max_smt_threads;
+
+static inline int topology_max_smt_threads(void)
+{
+ return __max_smt_threads;
+}
+
int topology_update_package_map(unsigned int apicid, unsigned int cpu);
extern int topology_phys_to_logical_pkg(unsigned int pkg);
#else
@@ -136,6 +144,7 @@ extern int topology_phys_to_logical_pkg(unsigned int pkg);
static inline int
topology_update_package_map(unsigned int apicid, unsigned int cpu) { return 0; }
static inline int topology_phys_to_logical_pkg(unsigned int pkg) { return 0; }
+static inline int topology_max_smt_threads(void) { return 1; }
#endif
static inline void arch_fix_phys_package_id(int num, u32 slot)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index fafe8b9..2ed0ec1 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -105,6 +105,9 @@ static unsigned int max_physical_pkg_id __read_mostly;
unsigned int __max_logical_packages __read_mostly;
EXPORT_SYMBOL(__max_logical_packages);
+/* Maximum number of SMT threads on any online core */
+int __max_smt_threads __read_mostly;
+
static inline void smpboot_setup_warm_reset_vector(unsigned long start_eip)
{
unsigned long flags;
@@ -493,7 +496,7 @@ void set_cpu_sibling_map(int cpu)
bool has_mp = has_smt || boot_cpu_data.x86_max_cores > 1;
struct cpuinfo_x86 *c = &cpu_data(cpu);
struct cpuinfo_x86 *o;
- int i;
+ int i, threads;
cpumask_set_cpu(cpu, cpu_sibling_setup_mask);
@@ -550,6 +553,10 @@ void set_cpu_sibling_map(int cpu)
if (match_die(c, o) && !topology_same_node(c, o))
primarily_use_numa_for_topology();
}
+
+ threads = cpumask_weight(topology_sibling_cpumask(cpu));
+ if (threads > __max_smt_threads)
+ __max_smt_threads = threads;
}
/* maps the cpu to the sched domain representing multi-core */
@@ -1441,6 +1448,21 @@ __init void prefill_possible_map(void)
#ifdef CONFIG_HOTPLUG_CPU
+/* Recompute SMT state for all CPUs on offline */
+static void recompute_smt_state(void)
+{
+ int max_threads, cpu;
+
+ max_threads = 0;
+ for_each_online_cpu (cpu) {
+ int threads = cpumask_weight(topology_sibling_cpumask(cpu));
+
+ if (threads > max_threads)
+ max_threads = threads;
+ }
+ __max_smt_threads = max_threads;
+}
+
static void remove_siblinginfo(int cpu)
{
int sibling;
@@ -1465,6 +1487,7 @@ static void remove_siblinginfo(int cpu)
c->phys_proc_id = 0;
c->cpu_core_id = 0;
cpumask_clear_cpu(cpu, cpu_sibling_setup_mask);
+ recompute_smt_state();
}
static void remove_cpu_from_maps(int cpu)
--
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