justin/jsix_import
1
0
Fork 0
Code Issues 1 Pull Requests Actions Packages Projects Releases Wiki Activity

[kernel] Add new threads to different CPUs

Browse Source 
Previously, when adding a new thread, we only ever added it to the
current CPU and relied on work stealing to balance the CPUs. This commit
has the scheduler schedule new tasks round-robin across CPUs in hopes of
having to steal fewer tasks.

Also adds the run_queue.prev pointer for debugging what task was just
running on the given CPU.
This commit is contained in:
Justin C. Miller
2022-03-13 18:07:08 -07:00
parent bb0d30610e
commit d759aae318
2 changed files with 11 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
src/kernel/scheduler.cpp
View File

@@ -29,6 +29,7 @@ scheduler *scheduler::s_instance = nullptr;
struct run_queue struct run_queue
{ {
tcb_node *current = nullptr; tcb_node *current = nullptr;
tcb_node *prev = nullptr;
tcb_list ready[scheduler::num_priorities]; tcb_list ready[scheduler::num_priorities];
tcb_list blocked; tcb_list blocked;
@@ -38,7 +39,7 @@ struct run_queue
}; };
scheduler::scheduler(unsigned cpus) : scheduler::scheduler(unsigned cpus) :
m_next_pid {1} m_add_index {0}
{ {
kassert(!s_instance, "Created multiple schedulers!"); kassert(!s_instance, "Created multiple schedulers!");
if (!s_instance) if (!s_instance)
@@ -108,11 +109,11 @@ scheduler::start()
void void
scheduler::add_thread(TCB *t) scheduler::add_thread(TCB *t)
{ {
cpu_data &cpu = current_cpu(); cpu_data *cpu = g_cpu_data[m_add_index++ % g_num_cpus];
run_queue &queue = m_run_queues[cpu.index]; run_queue &queue = m_run_queues[cpu->index];
util::scoped_lock lock {queue.lock}; util::scoped_lock lock {queue.lock};
t->cpu = &cpu; t->cpu = cpu;
t->time_left = quantum(t->priority); t->time_left = quantum(t->priority);
queue.blocked.push_back(static_cast<tcb_node*>(t)); queue.blocked.push_back(static_cast<tcb_node*>(t));
} }
@@ -232,6 +233,7 @@ scheduler::steal_work(cpu_data &cpu)
stolen += balance_lists(my_queue.ready[pri], other_queue.ready[pri], cpu); stolen += balance_lists(my_queue.ready[pri], other_queue.ready[pri], cpu);
stolen += balance_lists(my_queue.blocked, other_queue.blocked, cpu); stolen += balance_lists(my_queue.blocked, other_queue.blocked, cpu);
other_queue_lock.release();
if (stolen) if (stolen)
log::debug(logs::sched, "CPU%02x stole %2d tasks from CPU%02x", log::debug(logs::sched, "CPU%02x stole %2d tasks from CPU%02x",
@@ -313,6 +315,7 @@ scheduler::schedule()
return; return;
} }
queue.prev = queue.current;
thread *next_thread = next->thread; thread *next_thread = next->thread;
cpu.thread = next_thread; cpu.thread = next_thread;

6
src/kernel/scheduler.h
View File

@@ -5,6 +5,8 @@
#include <stdint.h> #include <stdint.h>
#include <util/vector.h> #include <util/vector.h>
extern cpu_data** g_cpu_data;
namespace kernel { namespace kernel {
namespace args { namespace args {
struct program; struct program;
@@ -86,14 +88,14 @@ public:
private: private:
friend class obj::process; friend class obj::process;
static constexpr uint64_t promote_frequency = 10; static constexpr uint64_t promote_frequency = 100;
static constexpr uint64_t steal_frequency = 10; static constexpr uint64_t steal_frequency = 10;
void prune(run_queue &queue, uint64_t now); void prune(run_queue &queue, uint64_t now);
void check_promotions(run_queue &queue, uint64_t now); void check_promotions(run_queue &queue, uint64_t now);
void steal_work(cpu_data &cpu); void steal_work(cpu_data &cpu);
uint32_t m_next_pid; uint32_t m_add_index;
uint32_t m_tick_count; uint32_t m_tick_count;
obj::process *m_kernel_process; obj::process *m_kernel_process;