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Kernel: Add Processor::pause() and use it to give the CPU a rest

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On x86, the "pause" instruction is a "spin loop hint".
This commit is contained in:
Andreas Kling 2021-08-08 15:27:04 +02:00
parent b7129c57df
commit 46215a8183
2 changed files with 9 additions and 4 deletions
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7
Kernel/Arch/x86/Processor.h
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@ -197,10 +197,15 @@ public:
return *g_total_processors.ptr(); return *g_total_processors.ptr();
} }
ALWAYS_INLINE static void pause()
{
asm volatile("pause");
}
ALWAYS_INLINE static void wait_check() ALWAYS_INLINE static void wait_check()
{ {
Processor::pause();
Processor::current().smp_process_pending_messages(); Processor::current().smp_process_pending_messages();
// TODO: pause
} }
[[noreturn]] static void halt(); [[noreturn]] static void halt();

6
Kernel/Arch/x86/common/Processor.cpp
View file

@ -682,7 +682,7 @@ ProcessorMessage& Processor::smp_get_from_pool()
msg = s_message_pool.load(AK::MemoryOrder::memory_order_consume); msg = s_message_pool.load(AK::MemoryOrder::memory_order_consume);
if (!msg) { if (!msg) {
if (!Processor::current().smp_process_pending_messages()) { if (!Processor::current().smp_process_pending_messages()) {
// TODO: pause for a bit? Processor::pause();
} }
continue; continue;
} }
@ -898,7 +898,7 @@ void Processor::smp_broadcast_wait_sync(ProcessorMessage& msg)
// If synchronous then we must cleanup and return the message back // If synchronous then we must cleanup and return the message back
// to the pool. Otherwise, the last processor to complete it will return it // to the pool. Otherwise, the last processor to complete it will return it
while (msg.refs.load(AK::MemoryOrder::memory_order_consume) != 0) { while (msg.refs.load(AK::MemoryOrder::memory_order_consume) != 0) {
// TODO: pause for a bit? Processor::pause();
// We need to process any messages that may have been sent to // We need to process any messages that may have been sent to
// us while we're waiting. This also checks if another processor // us while we're waiting. This also checks if another processor
@ -928,7 +928,7 @@ void Processor::smp_unicast_message(u32 cpu, ProcessorMessage& msg, bool async)
// If synchronous then we must cleanup and return the message back // If synchronous then we must cleanup and return the message back
// to the pool. Otherwise, the last processor to complete it will return it // to the pool. Otherwise, the last processor to complete it will return it
while (msg.refs.load(AK::MemoryOrder::memory_order_consume) != 0) { while (msg.refs.load(AK::MemoryOrder::memory_order_consume) != 0) {
// TODO: pause for a bit? Processor::pause();
// We need to process any messages that may have been sent to // We need to process any messages that may have been sent to
// us while we're waiting. This also checks if another processor // us while we're waiting. This also checks if another processor