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[Threading] Add thread priority mapping with timer-driven quantum decay

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And default ignore_thread_priorities to false.

Map Xenon's 0-31 priority range across all 5 host priority levels
instead of collapsing 0-17 into kNormal.

Use timer-driven quantum decay (~20ms period) matching Xenon's
60-quantum / 3-per-tick cycle to prevent starvation by gradually lowering
effective priority for non-real-time threads (< 18), piggybacking on the
existing 1ms timestamp timer.
This commit is contained in:
Herman S.
2026-04-09 22:33:08 +09:00
parent 61c8eb0707
commit b3d8a21b72
7 changed files with 194 additions and 44 deletions
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38
src/xenia/kernel/xboxkrnl/xboxkrnl_threading.cc
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@@ -1583,8 +1583,6 @@ DECLARE_XBOXKRNL_EXPORT2(KeInitializeDpc, kThreading, kImplemented, kSketchy);
dword_result_t KeInsertQueueDpc_entry(pointer_t<XDPC> dpc, dword_t arg1,
dword_t arg2) {
assert_always("DPC does not dispatch yet; going to hang!");
uint32_t list_entry_ptr = dpc.guest_address() + 4;
// Lock dispatcher.
@@ -1602,9 +1600,43 @@ dword_result_t KeInsertQueueDpc_entry(pointer_t<XDPC> dpc, dword_t arg1,
dpc_list->Insert(list_entry_ptr);
// Dispatch the DPC inline on the calling thread. On real hardware DPCs
// are deferred to DISPATCH_IRQL on the target processor, but DPC routines
// access per-CPU state via r13 (KPCR) so they must run on a thread whose
// KPCR is valid for the target CPU. The calling thread's KPCR satisfies
// this for the common case (desired_cpu_number == 0, meaning current CPU).
// Inline dispatch also avoids latency issues with shared work queues.
uint32_t routine = dpc->routine;
if (routine) {
auto thread = XThread::GetCurrentThread();
if (thread) {
auto thread_state = thread->thread_state();
auto ppc_context = thread_state->context();
auto kpcr = ppc_context->TranslateVirtualGPR<X_KPCR*>(ppc_context->r[13]);
// If we're already inside a DPC (reentrant KeInsertQueueDpc from a DPC
// routine), skip the impersonation — we're already at DISPATCH_IRQL.
bool already_in_dpc = kpcr->prcb_data.dpc_active != 0;
DPCImpersonationScope dpc_scope{};
if (!already_in_dpc) {
kernel_state()->BeginDPCImpersonation(ppc_context, dpc_scope);
}
uint64_t args[] = {dpc.guest_address(), (uint64_t)dpc->context,
(uint64_t)arg1, (uint64_t)arg2};
kernel_state()->processor()->Execute(thread_state, routine, args,
xe::countof(args));
if (!already_in_dpc) {
kernel_state()->EndDPCImpersonation(ppc_context, dpc_scope);
}
}
}
return 1;
}
DECLARE_XBOXKRNL_EXPORT2(KeInsertQueueDpc, kThreading, kStub, kSketchy);
DECLARE_XBOXKRNL_EXPORT2(KeInsertQueueDpc, kThreading, kImplemented, kSketchy);
dword_result_t KeRemoveQueueDpc_entry(pointer_t<XDPC> dpc) {
bool result = false;