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[Perf] (TLS): applier lookup cache in one thread_local block

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swung0x48
2026-10-10 04:14:10 -04:00
parent 575be3532d
commit f7550322d4
1 changed files with 15 additions and 13 deletions
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MobileGL/MG_Pipe/PipeApply.cpp
+15 -13
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@@ -769,10 +769,14 @@ namespace MobileGL::MG_Pipe {
return groups;
}
thread_local MGPipeApplierState* t_applierCached = nullptr;
thread_local Uint64 t_applierCachedSession = 0;
thread_local Uint64 t_applierCachedContext = 0;
thread_local Uint64 t_applierCachedGeneration = 0;
// One block, so a hit is one TLS address computation rather than four (P15).
struct ApplierCache {
MGPipeApplierState* Applier = nullptr;
Uint64 Session = 0;
Uint64 Context = 0;
Uint64 Generation = 0;
};
constinit thread_local ApplierCache t_applierCache;
} // namespace
Uint64 MGPipeNextApplierSerialBase() {
@@ -804,19 +808,17 @@ namespace MobileGL::MG_Pipe {
MGPipeApplierKey key;
if (!resolve(&key)) return g_defaultApplier;
// THE FAST PATH, and the reason this is a cache rather than a lookup: this function is
// called from the backend per state read. A hit is three TLS loads, one atomic load and
// two compares; a miss is the registry, which only moves when a context is created,
// called from the backend per state read. A hit is one TLS block, one atomic load and
// the compares; a miss is the registry, which only moves when a context is created,
// destroyed or made current.
const Uint64 generation = g_applierRegistryGeneration.load(std::memory_order_acquire);
if (t_applierCached != nullptr && t_applierCachedGeneration == generation &&
t_applierCachedSession == key.SessionKey && t_applierCachedContext == key.ContextToken) {
return *t_applierCached;
ApplierCache& cache = t_applierCache;
if (cache.Applier != nullptr && cache.Generation == generation && cache.Session == key.SessionKey &&
cache.Context == key.ContextToken) {
return *cache.Applier;
}
MGPipeApplierState* const applier = FindApplierForKey(key);
t_applierCached = applier;
t_applierCachedSession = key.SessionKey;
t_applierCachedContext = key.ContextToken;
t_applierCachedGeneration = generation;
cache = {applier, key.SessionKey, key.ContextToken, generation};
return *applier;
}