forked from suyu/suyu
Kernel/IPC: Add a small delay after each SyncRequest to prevent thread starvation.
Ported from citra PR #3091 The delay specified here is from a Nintendo 3DS, and should be measured in a Nintendo Switch. This change is enough to prevent Puyo Puyo Tetris's main thread starvation.
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f6e548fbc0
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4 changed files with 62 additions and 49 deletions
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@ -57,18 +57,7 @@ void ServerSession::Acquire(Thread* thread) {
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pending_requesting_threads.pop_back();
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}
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ResultCode ServerSession::HandleSyncRequest(SharedPtr<Thread> thread) {
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// The ServerSession received a sync request, this means that there's new data available
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// from its ClientSession, so wake up any threads that may be waiting on a svcReplyAndReceive or
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// similar.
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Kernel::HLERequestContext context(this);
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u32* cmd_buf = (u32*)Memory::GetPointer(thread->GetTLSAddress());
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context.PopulateFromIncomingCommandBuffer(cmd_buf, *Kernel::g_current_process,
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Kernel::g_handle_table);
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// If the session has been converted to a domain, handle the doomain request
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if (IsDomain()) {
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ResultCode ServerSession::HandleDomainSyncRequest(Kernel::HLERequestContext& context) {
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auto& domain_message_header = context.GetDomainMessageHeader();
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if (domain_message_header) {
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// If there is a DomainMessageHeader, then this is CommandType "Request"
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@ -91,23 +80,54 @@ ResultCode ServerSession::HandleSyncRequest(SharedPtr<Thread> thread) {
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LOG_CRITICAL(IPC, "Unknown domain command=%d", domain_message_header->command.Value());
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ASSERT(false);
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}
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return RESULT_SUCCESS;
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}
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ResultCode ServerSession::HandleSyncRequest(SharedPtr<Thread> thread) {
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// The ServerSession received a sync request, this means that there's new data available
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// from its ClientSession, so wake up any threads that may be waiting on a svcReplyAndReceive or
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// similar.
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Kernel::HLERequestContext context(this);
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u32* cmd_buf = (u32*)Memory::GetPointer(thread->GetTLSAddress());
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context.PopulateFromIncomingCommandBuffer(cmd_buf, *Kernel::g_current_process,
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Kernel::g_handle_table);
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ResultCode result = RESULT_SUCCESS;
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// If the session has been converted to a domain, handle the domain request
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if (IsDomain()) {
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result = HandleDomainSyncRequest(context);
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// If there is no domain header, the regular session handler is used
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} else if (hle_handler != nullptr) {
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// If this ServerSession has an associated HLE handler, forward the request to it.
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result = hle_handler->HandleSyncRequest(context);
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}
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// If this ServerSession has an associated HLE handler, forward the request to it.
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ResultCode result{RESULT_SUCCESS};
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if (hle_handler != nullptr) {
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// Attempt to translate the incoming request's command buffer.
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ResultCode translate_result = TranslateHLERequest(this);
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if (translate_result.IsError())
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return translate_result;
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if (thread->status == THREADSTATUS_RUNNING) {
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// Put the thread to sleep until the server replies, it will be awoken in
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// svcReplyAndReceive for LLE servers.
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thread->status = THREADSTATUS_WAIT_IPC;
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result = hle_handler->HandleSyncRequest(context);
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if (hle_handler != nullptr) {
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// For HLE services, we put the request threads to sleep for a short duration to
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// simulate IPC overhead, but only if the HLE handler didn't put the thread to sleep for
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// other reasons like an async callback. The IPC overhead is needed to prevent
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// starvation when a thread only does sync requests to HLE services while a
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// lower-priority thread is waiting to run.
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// This delay was approximated in a homebrew application by measuring the average time
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// it takes for svcSendSyncRequest to return when performing the SetLcdForceBlack IPC
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// request to the GSP:GPU service in a n3DS with firmware 11.6. The measured values have
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// a high variance and vary between models.
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static constexpr u64 IPCDelayNanoseconds = 39000;
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thread->WakeAfterDelay(IPCDelayNanoseconds);
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} else {
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// Add the thread to the list of threads that have issued a sync request with this
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// server.
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pending_requesting_threads.push_back(std::move(thread));
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}
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}
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// If this ServerSession does not have an HLE implementation, just wake up the threads waiting
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// on it.
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@ -140,9 +160,4 @@ ServerSession::SessionPair ServerSession::CreateSessionPair(const std::string& n
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return std::make_tuple(std::move(server_session), std::move(client_session));
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}
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ResultCode TranslateHLERequest(ServerSession* server_session) {
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// TODO(Subv): Implement this function once multiple concurrent processes are supported.
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return RESULT_SUCCESS;
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}
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} // namespace Kernel
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@ -21,6 +21,7 @@ class ServerSession;
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class Session;
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class SessionRequestHandler;
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class Thread;
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class HLERequestContext;
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/**
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* Kernel object representing the server endpoint of an IPC session. Sessions are the basic CTR-OS
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@ -116,17 +117,12 @@ private:
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*/
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static ResultVal<SharedPtr<ServerSession>> Create(std::string name = "Unknown");
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/// Handles a SyncRequest to a domain, forwarding the request to the proper object or closing an
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/// object handle.
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ResultCode HandleDomainSyncRequest(Kernel::HLERequestContext& context);
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/// When set to True, converts the session to a domain at the end of the command
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bool convert_to_domain{};
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};
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/**
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* Performs command buffer translation for an HLE IPC request.
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* The command buffer from the ServerSession thread's TLS is copied into a
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* buffer and all descriptors in the buffer are processed.
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* TODO(Subv): Implement this function, currently we do not support multiple processes running at
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* once, but once that is implemented we'll need to properly translate all descriptors
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* in the command buffer.
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*/
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ResultCode TranslateHLERequest(ServerSession* server_session);
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} // namespace Kernel
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@ -284,6 +284,7 @@ void Thread::ResumeFromWait() {
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case THREADSTATUS_WAIT_SYNCH_ANY:
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case THREADSTATUS_WAIT_ARB:
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case THREADSTATUS_WAIT_SLEEP:
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case THREADSTATUS_WAIT_IPC:
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break;
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case THREADSTATUS_READY:
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@ -40,6 +40,7 @@ enum ThreadStatus {
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THREADSTATUS_READY, ///< Ready to run
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THREADSTATUS_WAIT_ARB, ///< Waiting on an address arbiter
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THREADSTATUS_WAIT_SLEEP, ///< Waiting due to a SleepThread SVC
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THREADSTATUS_WAIT_IPC, ///< Waiting for the reply from an IPC request
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THREADSTATUS_WAIT_SYNCH_ANY, ///< Waiting due to WaitSynch1 or WaitSynchN with wait_all = false
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THREADSTATUS_WAIT_SYNCH_ALL, ///< Waiting due to WaitSynchronizationN with wait_all = true
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THREADSTATUS_DORMANT, ///< Created but not yet made ready
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