Implement ftruncate abi

src/graphics/host_gpu/renderer/cache/multiLevelPageTable.h

@@ -7,8 +7,9 @@
 #include <array>
 #include <cstddef>
 #include <cstdint>
-#include <list>
+#include <cstring>
 #include <memory>
+#include <type_traits>
 #include <utility>
 #include <vector>
 
@@ -103,6 +104,158 @@ private:
 	size_t                               m_allocated_buckets = 0;
 };
 
+// Inline owner storage for page-table entries. Texture pages normally have only a
+// handful of owners, so avoid a heap allocation on the first 16 registrations.
+//
+// Owners are packed into live uint64_t objects instead of being constructed in
+// raw storage. This keeps sparse bucket construction cheap without relying on
+// subtle implicit-lifetime or pointer-provenance rules.
+template <typename OwnerT, size_t InlineCapacity = 16>
+class InlinePageOwnerList final {
+public:
+	using value_type = OwnerT;
+	using size_type  = size_t;
+
+	class const_iterator final {
+	public:
+		[[nodiscard]] OwnerT operator*() const noexcept { return m_owners->At(m_index); }
+		const_iterator&      operator++() noexcept {
+			++m_index;
+			return *this;
+		}
+		bool operator==(const const_iterator&) const = default;
+
+	private:
+		friend class InlinePageOwnerList;
+		const_iterator(const InlinePageOwnerList* owners, size_type index) noexcept
+		    : m_owners(owners), m_index(index) {}
+
+		const InlinePageOwnerList* m_owners = nullptr;
+		size_type                  m_index  = 0;
+	};
+
+	static_assert(InlineCapacity > 0);
+	static_assert(std::is_default_constructible_v<OwnerT>);
+	static_assert(std::is_trivially_copyable_v<OwnerT>);
+	static_assert(std::has_unique_object_representations_v<OwnerT>);
+	static_assert(sizeof(OwnerT) <= sizeof(uint64_t));
+
+	InlinePageOwnerList() noexcept {}
+	InlinePageOwnerList(const InlinePageOwnerList&)            = delete;
+	InlinePageOwnerList& operator=(const InlinePageOwnerList&) = delete;
+	InlinePageOwnerList(InlinePageOwnerList&& other) noexcept
+	    : m_overflow(std::move(other.m_overflow)),
+	      m_inline_size(std::exchange(other.m_inline_size, 0)) {
+		if (m_overflow == nullptr) {
+			std::copy_n(other.m_inline.begin(), m_inline_size, m_inline.begin());
+		}
+	}
+	InlinePageOwnerList& operator=(InlinePageOwnerList&& other) noexcept {
+		if (this != &other) {
+			m_overflow    = std::move(other.m_overflow);
+			m_inline_size = std::exchange(other.m_inline_size, 0);
+			if (m_overflow == nullptr) {
+				std::copy_n(other.m_inline.begin(), m_inline_size, m_inline.begin());
+			}
+		}
+		return *this;
+	}
+
+	[[nodiscard]] const_iterator begin() const noexcept { return {this, 0}; }
+	[[nodiscard]] const_iterator end() const noexcept { return {this, size()}; }
+
+	[[nodiscard]] bool      empty() const noexcept { return size() == 0; }
+	[[nodiscard]] size_type size() const noexcept {
+		return m_overflow == nullptr ? m_inline_size : m_overflow->size();
+	}
+	[[nodiscard]] OwnerT front() const noexcept { return At(0); }
+	[[nodiscard]] OwnerT operator[](size_type index) const noexcept { return At(index); }
+
+	void push_back(const OwnerT& owner) {
+		const uint64_t packed = Pack(owner);
+		if (m_overflow != nullptr) {
+			m_overflow->push_back(packed);
+			return;
+		}
+		if (m_inline_size < InlineCapacity) {
+			m_inline[m_inline_size] = packed;
+			++m_inline_size;
+			return;
+		}
+		auto overflow = std::make_unique<std::vector<uint64_t>>();
+		overflow->reserve(InlineCapacity * 2);
+		overflow->assign(m_inline.begin(), m_inline.end());
+		overflow->push_back(packed);
+		m_overflow = std::move(overflow);
+	}
+
+	[[nodiscard]] bool Contains(const OwnerT& owner) const noexcept {
+		const uint64_t packed = Pack(owner);
+		if (m_overflow != nullptr) {
+			return std::find(m_overflow->begin(), m_overflow->end(), packed) != m_overflow->end();
+		}
+		return std::find(m_inline.begin(), m_inline.begin() + static_cast<ptrdiff_t>(m_inline_size),
+		                 packed) != m_inline.begin() + static_cast<ptrdiff_t>(m_inline_size);
+	}
+
+	[[nodiscard]] bool Erase(const OwnerT& owner) noexcept {
+		const uint64_t packed = Pack(owner);
+		if (m_overflow != nullptr) {
+			const auto found = std::find(m_overflow->begin(), m_overflow->end(), packed);
+			if (found == m_overflow->end()) {
+				return false;
+			}
+			m_overflow->erase(found);
+			if (m_overflow->size() == InlineCapacity) {
+				std::copy(m_overflow->begin(), m_overflow->end(), m_inline.begin());
+				m_inline_size = InlineCapacity;
+				m_overflow.reset();
+			}
+			return true;
+		}
+		const auto end   = m_inline.begin() + static_cast<ptrdiff_t>(m_inline_size);
+		const auto found = std::find(m_inline.begin(), end, packed);
+		if (found == end) {
+			return false;
+		}
+		std::move(found + 1, end, found);
+		--m_inline_size;
+		return true;
+	}
+
+	template <typename Func>
+	void ForEach(Func&& func) const {
+		if (m_overflow != nullptr) {
+			for (const uint64_t owner: *m_overflow) {
+				func(Unpack(owner));
+			}
+			return;
+		}
+		for (size_type index = 0; index < m_inline_size; ++index) {
+			func(Unpack(m_inline[index]));
+		}
+	}
+
+private:
+	[[nodiscard]] OwnerT At(size_type index) const noexcept {
+		return Unpack(m_overflow == nullptr ? m_inline[index] : (*m_overflow)[index]);
+	}
+	[[nodiscard]] static uint64_t Pack(const OwnerT& owner) noexcept {
+		uint64_t packed = 0;
+		std::memcpy(&packed, &owner, sizeof(owner));
+		return packed;
+	}
+	[[nodiscard]] static OwnerT Unpack(uint64_t packed) noexcept {
+		OwnerT owner {};
+		std::memcpy(&owner, &packed, sizeof(owner));
+		return owner;
+	}
+
+	std::array<uint64_t, InlineCapacity>   m_inline;
+	std::unique_ptr<std::vector<uint64_t>> m_overflow;
+	size_type                              m_inline_size = 0;
+};
+
 // Removes only the requested owner. Other owners in the same page entry remain intact.
 template <typename Container, typename Value>
 [[nodiscard]] bool EraseExact(Container& owners, const Value& owner) {
@@ -114,247 +267,6 @@ template <typename Container, typename Value>
 	return true;
 }
 
-// Multi-range ownership with 1 MiB candidate buckets and precise 4 KiB
-// lifetime accounting. OwnerT only needs equality.
-template <typename OwnerT>
-class MultiRangePageOwnerIndex final {
-private:
-	struct Registration;
-	using MembershipList = std::vector<const Registration*>;
-
-public:
-	struct ByteRange final {
-		uint64_t address = 0;
-		uint64_t size    = 0;
-	};
-
-	using CoarseTable   = MultiLevelPageTable<MembershipList, 20, 40, 10>;
-	using TrackingTable = MultiLevelPageTable<MembershipList, 12, 40, 18>;
-
-	[[nodiscard]] bool Register(const OwnerT& owner, const std::vector<ByteRange>& ranges) {
-		if (FindRegistration(owner) != m_registrations.end()) {
-			return false;
-		}
-		auto normalized = Normalize(ranges);
-		if (normalized.empty()) {
-			return false;
-		}
-		m_registrations.push_back({owner, std::move(normalized)});
-		const Registration* registration = &m_registrations.back();
-		for (const size_t page: CollectPages<20>(registration->ranges)) {
-			m_coarse_pages[page].push_back(registration);
-		}
-		for (const size_t page: CollectPages<12>(registration->ranges)) {
-			m_tracking_pages[page].push_back(registration);
-		}
-		return true;
-	}
-
-	// No state changes if an expected membership is absent. Final releases are
-	// sorted and coalesced 4 KiB spans whose final owner disappeared.
-	[[nodiscard]] bool Unregister(const OwnerT& owner, std::vector<ByteRange>& final_releases) {
-		final_releases.clear();
-		auto registration = FindRegistration(owner);
-		if (registration == m_registrations.end()) {
-			return false;
-		}
-		const auto          coarse_pages     = CollectPages<20>(registration->ranges);
-		const auto          tracking_pages   = CollectPages<12>(registration->ranges);
-		const Registration* registration_ptr = &*registration;
-		if (!HasAllMemberships(m_coarse_pages, coarse_pages, registration_ptr) ||
-		    !HasAllMemberships(m_tracking_pages, tracking_pages, registration_ptr)) {
-			return false;
-		}
-		std::vector<size_t> final_pages;
-		for (const size_t page: coarse_pages) {
-			(void)EraseExact(*m_coarse_pages.Find(page), registration_ptr);
-		}
-		for (const size_t page: tracking_pages) {
-			auto& owners = *m_tracking_pages.Find(page);
-			if (owners.size() == 1) {
-				final_pages.push_back(page);
-			}
-			(void)EraseExact(owners, registration_ptr);
-		}
-		m_registrations.erase(registration);
-		final_releases = CoalesceTrackingPages(final_pages);
-		return true;
-	}
-
-	[[nodiscard]] std::vector<OwnerT> Query(uint64_t address, uint64_t size) const {
-		return Query(address, size, [](const OwnerT&) { return true; });
-	}
-
-	template <typename Predicate>
-	[[nodiscard]] std::vector<OwnerT> Query(uint64_t address, uint64_t size,
-	                                        Predicate&& predicate) const {
-		return QueryImpl(address, size, true, std::forward<Predicate>(predicate));
-	}
-
-	// Fault paths use page candidates: exact byte-disjoint owners sharing a
-	// touched 4 KiB page are intentionally retained.
-	[[nodiscard]] std::vector<OwnerT> QueryCandidates(uint64_t address, uint64_t size) const {
-		return QueryCandidates(address, size, [](const OwnerT&) { return true; });
-	}
-
-	template <typename Predicate>
-	[[nodiscard]] std::vector<OwnerT> QueryCandidates(uint64_t address, uint64_t size,
-	                                                  Predicate&& predicate) const {
-		return QueryImpl(address, size, false, std::forward<Predicate>(predicate));
-	}
-
-	[[nodiscard]] size_t CoarseMembershipCount(size_t page) const {
-		const auto* owners = m_coarse_pages.Find(page);
-		return owners == nullptr ? 0 : owners->size();
-	}
-	[[nodiscard]] size_t TrackingMembershipCount(size_t page) const {
-		const auto* owners = m_tracking_pages.Find(page);
-		return owners == nullptr ? 0 : owners->size();
-	}
-
-private:
-	template <typename Predicate>
-	[[nodiscard]] std::vector<OwnerT> QueryImpl(uint64_t address, uint64_t size, bool strict_bytes,
-	                                            Predicate&& predicate) const {
-		typename CoarseTable::PageRange   coarse_range {};
-		typename TrackingTable::PageRange tracking_range {};
-		if (!CoarseTable::TryGetPageRange(address, size, coarse_range) ||
-		    (!strict_bytes && !TrackingTable::TryGetPageRange(address, size, tracking_range))) {
-			return {};
-		}
-		MembershipList candidates;
-		for (size_t page = coarse_range.first; page < coarse_range.last_exclusive; ++page) {
-			if (const auto* owners = m_coarse_pages.Find(page); owners != nullptr) {
-				AppendUnique(candidates, *owners);
-			}
-		}
-		std::vector<OwnerT> result;
-		for (const Registration* registration: candidates) {
-			if ((strict_bytes ? Overlaps(registration->ranges, address, size)
-			                  : HasTrackingMembership(registration, tracking_range)) &&
-			    predicate(registration->owner)) {
-				result.push_back(registration->owner);
-			}
-		}
-		return result;
-	}
-
-	struct Registration final {
-		OwnerT                 owner;
-		std::vector<ByteRange> ranges;
-	};
-	using RegistrationIterator      = typename std::list<Registration>::iterator;
-	using ConstRegistrationIterator = typename std::list<Registration>::const_iterator;
-
-	[[nodiscard]] RegistrationIterator FindRegistration(const OwnerT& owner) {
-		return std::find_if(m_registrations.begin(), m_registrations.end(),
-		                    [&](const Registration& item) { return item.owner == owner; });
-	}
-	[[nodiscard]] ConstRegistrationIterator FindRegistration(const OwnerT& owner) const {
-		return std::find_if(m_registrations.begin(), m_registrations.end(),
-		                    [&](const Registration& item) { return item.owner == owner; });
-	}
-
-	[[nodiscard]] static std::vector<ByteRange> Normalize(const std::vector<ByteRange>& ranges) {
-		std::vector<ByteRange> sorted;
-		for (const auto& range: ranges) {
-			typename CoarseTable::PageRange ignored {};
-			if (!CoarseTable::TryGetPageRange(range.address, range.size, ignored)) {
-				return {};
-			}
-			sorted.push_back(range);
-		}
-		std::sort(sorted.begin(), sorted.end(), [](const ByteRange& lhs, const ByteRange& rhs) {
-			return lhs.address < rhs.address;
-		});
-		std::vector<ByteRange> merged;
-		for (const auto& range: sorted) {
-			if (merged.empty() || range.address > merged.back().address + merged.back().size) {
-				merged.push_back(range);
-			} else {
-				const uint64_t end = std::max(merged.back().address + merged.back().size,
-				                              range.address + range.size);
-				merged.back().size = end - merged.back().address;
-			}
-		}
-		return merged;
-	}
-
-	template <size_t Bits>
-	[[nodiscard]] static std::vector<size_t> CollectPages(const std::vector<ByteRange>& ranges) {
-		std::vector<size_t> pages;
-		for (const auto& range: ranges) {
-			const size_t first = static_cast<size_t>(range.address >> Bits);
-			const size_t last  = static_cast<size_t>((range.address + range.size - 1) >> Bits);
-			for (size_t page = first; page <= last; ++page) {
-				pages.push_back(page);
-			}
-		}
-		std::sort(pages.begin(), pages.end());
-		pages.erase(std::unique(pages.begin(), pages.end()), pages.end());
-		return pages;
-	}
-
-	template <typename Table>
-	[[nodiscard]] static bool HasAllMemberships(const Table&               table,
-	                                            const std::vector<size_t>& pages,
-	                                            const Registration*        registration) {
-		for (const size_t page: pages) {
-			const auto* owners = table.Find(page);
-			if (owners == nullptr ||
-			    std::find(owners->begin(), owners->end(), registration) == owners->end()) {
-				return false;
-			}
-		}
-		return true;
-	}
-
-	[[nodiscard]] bool HasTrackingMembership(const Registration*                      registration,
-	                                         const typename TrackingTable::PageRange& range) const {
-		for (size_t page = range.first; page < range.last_exclusive; ++page) {
-			const auto* owners = m_tracking_pages.Find(page);
-			if (owners != nullptr &&
-			    std::find(owners->begin(), owners->end(), registration) != owners->end()) {
-				return true;
-			}
-		}
-		return false;
-	}
-
-	[[nodiscard]] static bool Overlaps(const std::vector<ByteRange>& ranges, uint64_t address,
-	                                   uint64_t size) {
-		const uint64_t end = address + size;
-		return std::any_of(ranges.begin(), ranges.end(), [&](const ByteRange& range) {
-			return range.address < end && address < range.address + range.size;
-		});
-	}
-	static void AppendUnique(MembershipList& destination, const MembershipList& source) {
-		for (const Registration* registration: source) {
-			if (std::find(destination.begin(), destination.end(), registration) ==
-			    destination.end()) {
-				destination.push_back(registration);
-			}
-		}
-	}
-	[[nodiscard]] static std::vector<ByteRange>
-	CoalesceTrackingPages(const std::vector<size_t>& pages) {
-		std::vector<ByteRange> result;
-		for (const size_t page: pages) {
-			const uint64_t address = static_cast<uint64_t>(page) << 12;
-			if (!result.empty() && result.back().address + result.back().size == address) {
-				result.back().size += uint64_t {1} << 12;
-			} else {
-				result.push_back({address, uint64_t {1} << 12});
-			}
-		}
-		return result;
-	}
-
-	CoarseTable             m_coarse_pages;
-	TrackingTable           m_tracking_pages;
-	std::list<Registration> m_registrations;
-};
-
 } // namespace Libs::Graphics
 
 #endif // EMULATOR_SRC_GRAPHICS_HOST_GPU_RENDERER_MULTILEVELPAGETABLE_H_

src/graphics/host_gpu/renderer/cache/textureCache.cpp

@@ -195,10 +195,12 @@ void TextureCache::RegisterImage(ImageId id) {
 	if (image.registered || image.info.data.Empty()) {
 		EXIT("TextureCache: invalid image registration\n");
 	}
-	std::vector<ImageOwnerIndex::ByteRange> ranges;
-	ranges.push_back({image.info.data.address, image.info.data.size});
-	if (!m_image_owner_index.Register(id, ranges)) {
-		EXIT("TextureCache: duplicate or invalid image registration\n");
+	ImagePageTable::PageRange pages {};
+	if (!ImagePageTable::TryGetPageRange(image.info.data.address, image.info.data.size, pages)) {
+		EXIT("TextureCache: image registration is outside the guest address space\n");
+	}
+	for (size_t page = pages.first; page < pages.last_exclusive; ++page) {
+		m_image_page_table[page].push_back(id);
 	}
 	image.registered = true;
 	image.lru_id     = m_lru_cache.Insert(id, m_gc_tick);
@@ -211,9 +213,15 @@ void TextureCache::UnregisterImage(ImageId id) {
 		return;
 	}
 	UntrackImage(id);
-	std::vector<ImageOwnerIndex::ByteRange> releases;
-	if (!m_image_owner_index.Unregister(id, releases)) {
-		EXIT("TextureCache: image missing from owner index\n");
+	ImagePageTable::PageRange pages {};
+	if (!ImagePageTable::TryGetPageRange(image.info.data.address, image.info.data.size, pages)) {
+		EXIT("TextureCache: registered image is outside the guest address space\n");
+	}
+	for (size_t page = pages.first; page < pages.last_exclusive; ++page) {
+		auto* owners = m_image_page_table.Find(page);
+		if (owners == nullptr || !owners->Erase(id)) {
+			EXIT("TextureCache: image missing from page owner index\n");
+		}
 	}
 	m_lru_cache.Free(image.lru_id);
 	const auto accounted = image.AccountedSize();
@@ -451,10 +459,48 @@ const Image& TextureCache::GetImage(ImageId id) const {
 	return ResolveImage(id);
 }
 
-std::vector<ImageId> TextureCache::FindImagesInRegion(uint64_t address, uint64_t size,
-                                                      bool page_overlap) const {
-	return page_overlap ? m_image_owner_index.QueryCandidates(address, size)
-	                    : m_image_owner_index.Query(address, size);
+TextureCache::ImageIds TextureCache::FindImagesInRegion(uint64_t address, uint64_t size,
+                                                        bool page_overlap) const {
+	ImagePageTable::PageRange pages {};
+	if (!ImagePageTable::TryGetPageRange(address, size, pages)) {
+		return {};
+	}
+
+	uint32_t query_epoch = ++m_image_query_epoch;
+	if (query_epoch == 0) {
+		for (const auto& slot: m_slots) {
+			if (slot.image != nullptr) {
+				slot.image->query_epoch = 0;
+			}
+		}
+		query_epoch = ++m_image_query_epoch;
+	}
+
+	ImageIds result;
+	for (size_t page = pages.first; page < pages.last_exclusive; ++page) {
+		const auto* owners = m_image_page_table.Find(page);
+		if (owners == nullptr) {
+			continue;
+		}
+		owners->ForEach([&](ImageId id) {
+			if (!id || id.index >= m_slots.size()) {
+				return;
+			}
+			const auto& slot = m_slots[id.index];
+			if (slot.generation != id.generation || slot.image == nullptr) {
+				return;
+			}
+			auto& image = *slot.image;
+			if (image.query_epoch == query_epoch) {
+				return;
+			}
+			image.query_epoch = query_epoch;
+			if (image.Overlaps(address, size, page_overlap)) {
+				result.push_back(id);
+			}
+		});
+	}
+	return result;
 }
 
 ImageId TextureCache::GetNullImage(const ImageDesc& desc) {
@@ -1152,9 +1198,9 @@ ImageId TextureCache::FindImage(ImageDesc& desc, bool exact_format) {
 	ImageId result {};
 	bool    inserted_new = false;
 	{
-		std::lock_guard            transaction(m_resource_mutex);
-		CacheLock                  lock(*this, m_lock);
-		const std::vector<ImageId> candidates =
+		std::lock_guard transaction(m_resource_mutex);
+		CacheLock       lock(*this, m_lock);
+		const auto      candidates =
 		    FindImagesInRegion(desc.info.data.address, desc.info.data.size, false);
 
 		for (const auto id: candidates) {

src/graphics/host_gpu/renderer/cache/textureCache.h

@@ -99,7 +99,8 @@ private:
 		int32_t layer = -1;
 	};
 
-	using ImageOwnerIndex = MultiRangePageOwnerIndex<ImageId>;
+	using ImageIds       = InlinePageOwnerList<ImageId, 16>;
+	using ImagePageTable = MultiLevelPageTable<ImageIds, 20, 40, 10>;
 
 	[[nodiscard]] Image&                 ResolveImage(ImageId id);
 	[[nodiscard]] const Image&           ResolveImage(ImageId id) const;
@@ -125,8 +126,9 @@ private:
 	[[nodiscard]] static BindingType UploadBinding(const Image& image);
 	[[nodiscard]] bool               SafeToDownload(const Image& image);
 
-	[[nodiscard]] std::vector<ImageId> FindImagesInRegion(uint64_t address, uint64_t size,
-	                                                      bool page_overlap) const;
+	// Caller holds m_lock; it also serializes the per-image query epoch.
+	[[nodiscard]] ImageIds      FindImagesInRegion(uint64_t address, uint64_t size,
+	                                               bool page_overlap) const;
 	[[nodiscard]] OverlapResult ResolveOverlap(const ImageInfo& requested, BindingType binding,
 	                                           ImageId cached, ImageId merged);
 	[[nodiscard]] ImageId       ResolveDepthOverlap(const ImageInfo& requested, BindingType binding,
@@ -169,7 +171,7 @@ private:
 	ResourceMutex&                                    m_resource_mutex;
 	std::vector<Slot>                                 m_slots;
 	std::vector<uint32_t>                             m_free_slots;
-	ImageOwnerIndex                                   m_image_owner_index;
+	ImagePageTable                                    m_image_page_table;
 	std::map<vk::Format, ImageId>                     m_null_images;
 	Common::LeastRecentlyUsedCache<ImageId, uint64_t> m_lru_cache;
 	std::set<ImageId>                                 m_download_images;
@@ -177,9 +179,10 @@ private:
 	uint64_t                                          m_total_used_memory  = 0;
 	uint64_t                                          m_trigger_gc_memory  = 0;
 	uint64_t                                          m_pressure_gc_memory = 1536ull * 1024 * 1024;
-	uint64_t m_critical_gc_memory     = 3ull * 1024 * 1024 * 1024;
-	uint64_t m_gc_tick                = 0;
-	bool     m_readback_linear_images = false;
+	uint64_t         m_critical_gc_memory     = 3ull * 1024 * 1024 * 1024;
+	uint64_t         m_gc_tick                = 0;
+	mutable uint32_t m_image_query_epoch      = 0;
+	bool             m_readback_linear_images = false;
 
 	friend struct TextureCacheTestAccess;
 	friend class BufferCache;

src/graphics/host_gpu/renderer/image/image.h

@@ -154,17 +154,18 @@ public:
 	}
 	[[nodiscard]] uint64_t HashGuestEdges() const;
 
-	ImageInfo      info;
-	VulkanImage    backing;
-	ImageViewCache views;
-	ImageUsage     usage;
-	ImageBinding   binding;
-	bool           registered     = false;
-	uint64_t       track_addr     = 0;
-	uint64_t       track_addr_end = 0;
-	ImageId        depth_id {};
-	uint64_t       tick_accessed_last = 0;
-	size_t         lru_id             = 0;
+	ImageInfo        info;
+	VulkanImage      backing;
+	ImageViewCache   views;
+	ImageUsage       usage;
+	ImageBinding     binding;
+	bool             registered     = false;
+	mutable uint32_t query_epoch    = 0;
+	uint64_t         track_addr     = 0;
+	uint64_t         track_addr_end = 0;
+	ImageId          depth_id {};
+	uint64_t         tick_accessed_last = 0;
+	size_t           lru_id             = 0;
 
 private:
 	friend struct ImageTestAccess;

src/kernel/fileSystem.cpp

@@ -64,6 +64,7 @@ struct File {
 	std::filesystem::path               real_name;
 	std::atomic_bool                    opened;
 	std::atomic_bool                    directory;
+	std::atomic_bool                    writable;
 	std::atomic_bool                    append;
 	std::atomic_bool                    sync_writes;
 	SpecialFile                         special;
@@ -129,6 +130,7 @@ int FileDescriptors::CreateDescriptor() {
 	auto* file        = new File {};
 	file->opened      = false;
 	file->directory   = false;
+	file->writable    = false;
 	file->append      = false;
 	file->sync_writes = false;
 	file->special     = SpecialFile::None;
@@ -408,6 +410,7 @@ int KYTY_SYSV_ABI KernelOpen(const char* path, int flags, uint16_t mode) {
 	EXIT_IF(file == nullptr || file->opened || file->directory);
 
 	file->name        = path;
+	file->writable    = rw_mode != Common::File::Mode::Read;
 	file->append      = append;
 	file->sync_writes = fsync || sync || dsync;
 
@@ -953,6 +956,47 @@ int KYTY_SYSV_ABI KernelFstat(int d, FileStat* sb) {
 	return OK;
 }
 
+int KYTY_SYSV_ABI KernelFtruncate(int d, int64_t length) {
+	PRINT_NAME();
+
+	if (d < DESCRIPTOR_MIN) {
+		return KERNEL_ERROR_EBADF;
+	}
+
+	if (length < 0) {
+		return KERNEL_ERROR_EINVAL;
+	}
+
+	if (::Libs::Network::Net::IsSocket(d)) {
+		return KERNEL_ERROR_EINVAL;
+	}
+
+	auto* file = g_files->GetFile(d);
+
+	if (file == nullptr || !file->opened) {
+		return KERNEL_ERROR_EBADF;
+	}
+
+	if (!file->writable) {
+		return KERNEL_ERROR_EBADF;
+	}
+
+	if (file->directory || file->special != SpecialFile::None) {
+		return KERNEL_ERROR_EINVAL;
+	}
+
+	Common::LockGuard lock(file->mutex);
+
+	if (file->f.IsInvalid() || !file->f.Truncate(static_cast<uint64_t>(length))) {
+		return KERNEL_ERROR_EIO;
+	}
+
+	LOGF("\tFtruncate (size = %" PRId64 ") file: %s\n", length,
+	     Common::PathToString(file->real_name).c_str());
+
+	return OK;
+}
+
 int KYTY_SYSV_ABI KernelUnlink(const char* path) {
 	PRINT_NAME();
 

src/kernel/fileSystem.h

@@ -48,6 +48,7 @@ int64_t KYTY_SYSV_ABI KernelPwrite(int d, const void* buf, size_t nbytes, int64_
 int64_t KYTY_SYSV_ABI KernelLseek(int d, int64_t offset, int whence);
 int KYTY_SYSV_ABI     KernelStat(const char* path, FileStat* sb);
 int KYTY_SYSV_ABI     KernelFstat(int d, FileStat* sb);
+int KYTY_SYSV_ABI     KernelFtruncate(int d, int64_t length);
 int KYTY_SYSV_ABI     KernelUnlink(const char* path);
 int KYTY_SYSV_ABI     KernelRename(const char* from, const char* to);
 int KYTY_SYSV_ABI     KernelGetdirentries(int fd, char* buf, int nbytes, int64_t* basep);

src/libs/libKernel.cpp

@@ -2021,6 +2021,12 @@ int64_t KYTY_SYSV_ABI fstat(int d, LibKernel::FileSystem::FileStat* sb) {
 	return POSIX_N_CALL(LibKernel::FileSystem::KernelFstat(d, sb));
 }
 
+int KYTY_SYSV_ABI ftruncate(int d, int64_t length) {
+	PRINT_NAME();
+
+	return POSIX_CALL(LibKernel::FileSystem::KernelFtruncate(d, length));
+}
+
 int KYTY_SYSV_ABI socket(int family, int type, int protocol) {
 	PRINT_NAME();
 	return Network::Net::Socket(family, type, protocol);
@@ -2159,6 +2165,7 @@ LIB_DEFINE(InitLibKernel_1_Posix) {
 	LIB_FUNC("yS8U2TGCe1A", nanosleep);
 	LIB_FUNC("E6ao34wPw+U", stat);
 	LIB_FUNC("JGMio+21L4c", mkdir);
+	LIB_FUNC("ih4CD9-gghM", Posix::ftruncate);
 	LIB_FUNC("pDuPEf3m4fI", Posix::sem_init);
 	LIB_FUNC("cDW233RAwWo", Posix::sem_destroy);
 	LIB_FUNC("YCV5dGGBcCo", Posix::sem_wait);

tests/ImagePageTableTests.cpp

@@ -3,13 +3,15 @@
 #include <cstdint>
 #include <cstdio>
 #include <cstdlib>
+#include <utility>
 #include <vector>
 
 namespace {
 
 using Owners     = std::vector<uint32_t>;
 using Table      = Libs::Graphics::MultiLevelPageTable<Owners>;
-using OwnerIndex = Libs::Graphics::MultiRangePageOwnerIndex<uint32_t>;
+using PageOwners = Libs::Graphics::InlinePageOwnerList<uint32_t, 16>;
+using OwnerTable = Libs::Graphics::MultiLevelPageTable<PageOwners, 20, 40, 10>;
 
 void Check(bool value, const char* text) {
 	if (!value) {
@@ -77,76 +79,93 @@ void TestAddressSpaceBoundaries() {
 	      "final page supports allocating and nonallocating access");
 }
 
-void TestMultiRangeRegistrationDeduplicatesPages() {
-	OwnerIndex index;
-	// Depth and stencil-like planes overlap tracking pages and share one 1 MiB bucket.
-	Check(index.Register(7, {{0x101000, 0x2800}, {0x102000, 0x3000}}),
-	      "multi-range owner registers");
-	Check(index.CoarseMembershipCount(1) == 1,
-	      "one owner is inserted once in a shared 1 MiB bucket");
-	Check(index.TrackingMembershipCount(0x102) == 1,
-	      "overlapping planes insert one 4 KiB membership");
-	Check(!index.Register(7, {{0x101000, 0x1000}}), "duplicate owner registration hard-fails");
+void TestInlineOwnerStorageAndOverflow() {
+	PageOwners owners;
+	for (uint32_t owner = 1; owner <= 18; ++owner) {
+		owners.push_back(owner);
+	}
+	Check(owners.size() == 18 && owners.front() == 1,
+	      "inline owner storage grows past its 16-owner capacity");
+	uint32_t expected = 1;
+	for (const uint32_t owner: owners) {
+		Check(owner == expected++, "overflow preserves registration order");
+	}
+	Check(owners.Erase(5) && owners.size() == 17 && !owners.Contains(5),
+	      "overflow erase removes only the requested owner");
+	Check(owners.Erase(18) && owners.size() == 16,
+	      "overflow storage shrinks back to inline capacity");
+	const std::vector<uint32_t> remaining {1, 2, 3, 4, 6, 7, 8, 9,
+	                                       10, 11, 12, 13, 14, 15, 16, 17};
+	size_t                      remaining_index = 0;
+	for (const uint32_t owner: owners) {
+		Check(owner == remaining[remaining_index++],
+		      "overflow-to-inline shrink preserves every owner");
+	}
+	Check(!owners.Erase(99), "missing inline owner is reported without mutation");
 
-	const auto owners = index.Query(0x100000, 0x10000);
-	Check(owners.size() == 1 && owners.front() == 7, "multi-page query returns an owner once");
+	PageOwners moved = std::move(owners);
+	Check(owners.empty() && moved.size() == remaining.size() && moved.front() == 1,
+	      "moving a full inline owner list leaves the source empty");
+	PageOwners partial;
+	partial.push_back(41);
+	partial.push_back(42);
+	PageOwners partial_moved = std::move(partial);
+	Check(partial.empty() && partial_moved.size() == 2 && partial_moved[1] == 42,
+	      "moving a partially populated list copies only live owners");
+	PageOwners assigned;
+	assigned.push_back(99);
+	assigned = std::move(partial_moved);
+	Check(partial_moved.empty() && assigned.size() == 2 && assigned.front() == 41,
+	      "move assignment replaces an inline list without reading inactive slots");
+	PageOwners empty;
+	PageOwners empty_moved = std::move(empty);
+	Check(empty.empty() && empty_moved.empty(), "moving an empty owner list is safe");
 }
 
-void TestSharedPageUnregisterLifecycle() {
-	OwnerIndex                               index;
-	const std::vector<OwnerIndex::ByteRange> ranges {{0x202000, 0x2000}};
-	Check(index.Register(11, ranges) && index.Register(22, ranges),
-	      "two owners register on identical pages");
-	Check(index.CoarseMembershipCount(2) == 2 && index.TrackingMembershipCount(0x202) == 2,
-	      "coarse and tracking pages retain both owners");
-
-	std::vector<OwnerIndex::ByteRange> releases;
-	Check(index.Unregister(11, releases), "first owner unregisters");
-	Check(releases.empty(), "shared tracking pages are not released with one owner remaining");
-	Check(index.Query(0x202000, 1).size() == 1 && index.Query(0x202000, 1).front() == 22,
-	      "unregistering one owner preserves the other");
-	Check(!index.Unregister(11, releases), "missing membership hard-fails without mutation");
-
-	Check(index.Unregister(22, releases), "final owner unregisters");
-	Check(releases.size() == 1 && releases.front().address == 0x202000 &&
-	          releases.front().size == 0x2000,
-	      "adjacent final-owner tracking pages return one contiguous release");
+void TestOneMiBRegistrationGranularity() {
+	static_assert(OwnerTable::kPageBits == 20);
+	OwnerTable            table;
+	OwnerTable::PageRange pages {};
+	constexpr uint64_t    range_size = 64ull * 1024 * 1024;
+	Check(OwnerTable::TryGetPageRange(0, range_size, pages), "large owner range is valid");
+	Check(pages.first == 0 && pages.last_exclusive == 64,
+	      "64 MiB registration touches exactly 64 one-MiB entries");
+	for (size_t page = pages.first; page < pages.last_exclusive; ++page) {
+		table[page].push_back(7);
+	}
+	Check(table.AllocatedBucketCount() == 1,
+	      "large registration uses one sparse second-level bucket");
+	for (size_t page = pages.first; page < pages.last_exclusive; ++page) {
+		auto* owners = table.Find(page);
+		Check(owners != nullptr && owners->size() == 1 && owners->front() == 7,
+		      "each touched one-MiB entry retains the owner once");
+		Check(owners->Erase(7), "large owner unregisters by coarse page");
+	}
 }
 
-void TestStrictByteFilteringAndPredicate() {
-	OwnerIndex index;
-	Check(index.Register(31, {{0x300100, 0x100}}), "first byte-disjoint owner registers");
-	Check(index.Register(32, {{0x300800, 0x100}}), "second byte-disjoint owner registers");
-	Check(index.Register(33, {{0x30f000, 0x100}}), "coarse-only owner registers");
-	Check(index.TrackingMembershipCount(0x300) == 2,
-	      "byte-disjoint owners share one tracking page");
-	Check(index.CoarseMembershipCount(3) == 3,
-	      "all owners share one coarse candidate bucket");
-	Check(index.Query(0x300400, 0x40).empty(), "page hit without byte overlap is filtered out");
-	const auto page_candidates = index.QueryCandidates(0x300400, 0x40);
-	Check(page_candidates.size() == 2,
-	      "fault candidate query retains touched-page owners and rejects coarse-only owners");
-	const auto first = index.Query(0x300180, 0x10);
-	Check(first.size() == 1 && first.front() == 31,
-	      "strict byte overlap selects only the matching owner");
-	const auto predicate_filtered =
-	    index.Query(0x300000, 0x1000, [](uint32_t owner) { return owner == 32; });
-	Check(predicate_filtered.size() == 1 && predicate_filtered.front() == 32,
-	      "supplied predicate filters query owners");
+void TestSharedCoarsePageLifecycle() {
+	OwnerTable table;
+	auto&      owners = table[2];
+	owners.push_back(11);
+	owners.push_back(22);
+	Check(owners.size() == 2, "two images share one coarse page");
+	Check(owners.Erase(11) && owners.size() == 1 && owners.front() == 22,
+	      "unregistering one image preserves its coarse-page neighbor");
+	Check(!owners.Erase(11), "double unregister is rejected without mutation");
+	Check(owners.Erase(22) && owners.empty(), "final coarse-page owner unregisters");
 }
 
-void TestOwnerIndexAddressSpaceBoundary() {
-	OwnerIndex         index;
-	constexpr uint64_t last_byte = OwnerIndex::CoarseTable::kAddressSpaceSize - 1;
-	Check(index.Register(41, {{last_byte, 1}}), "final guest byte registers");
-	const auto exact = index.Query(last_byte, 1);
-	Check(exact.size() == 1 && exact.front() == 41,
-	      "strict query finds an exact overlap at the final guest byte");
-	Check(index.Query(last_byte - 1, 1).empty(),
-	      "strict query preserves half-open overlap boundaries");
-	const auto page_candidates = index.QueryCandidates(last_byte - 1, 1);
-	Check(page_candidates.size() == 1 && page_candidates.front() == 41,
-	      "page candidate query retains a byte-disjoint owner on the final tracking page");
+void TestOneMiBBoundaries() {
+	OwnerTable::PageRange range {};
+	Check(OwnerTable::TryGetPageRange(0x0fffff, 2, range),
+	      "range crossing a one-MiB boundary is valid");
+	Check(range.first == 0 && range.last_exclusive == 2,
+	      "cross-boundary registration touches both coarse pages");
+	Check(OwnerTable::TryGetPageRange(OwnerTable::kAddressSpaceSize - 1, 1, range),
+	      "final guest byte maps to a coarse owner page");
+	Check(range.first == OwnerTable::kPageCount - 1 &&
+	          range.last_exclusive == OwnerTable::kPageCount,
+	      "final guest byte uses the final one-MiB page");
 }
 
 } // namespace
@@ -156,10 +175,10 @@ int main() {
 	TestCrossBucketRange();
 	TestQueriesDoNotAllocate();
 	TestAddressSpaceBoundaries();
-	TestMultiRangeRegistrationDeduplicatesPages();
-	TestSharedPageUnregisterLifecycle();
-	TestStrictByteFilteringAndPredicate();
-	TestOwnerIndexAddressSpaceBoundary();
+	TestInlineOwnerStorageAndOverflow();
+	TestOneMiBRegistrationGranularity();
+	TestSharedCoarsePageLifecycle();
+	TestOneMiBBoundaries();
 	std::printf("ImagePageTableTests: all cases passed\n");
 	return 0;
 }

tests/ShaderRecompilerComputeTests.cpp

@@ -163,6 +163,10 @@ struct TileManagerTestAccess {
 };
 
 struct TextureCacheTestAccess {
+	static_assert(TextureCache::ImagePageTable::kPageBits == 20);
+	static_assert(TextureCache::ImagePageTable::kAddressSpaceBits == 40);
+	static_assert(TextureCache::ImagePageTable::kFirstLevelBits == 10);
+
 	static void ConfigureGarbageCollection(TextureCache& cache, std::span<const ImageId> oldest,
 	                                       uint64_t tick, uint64_t pressure) {
 		cache.m_trigger_gc_memory  = 0;
@@ -197,6 +201,75 @@ struct TextureCacheTestAccess {
 		return owner != nullptr && owner->registered;
 	}
 
+	static std::vector<ImageId> FindImages(TextureCache& cache, uint64_t address, uint64_t size,
+	                                       bool page_overlap) {
+		std::lock_guard      lock(cache.m_lock);
+		const auto           found = cache.FindImagesInRegion(address, size, page_overlap);
+		std::vector<ImageId> result;
+		result.reserve(found.size());
+		for (const auto id: found) {
+			result.push_back(id);
+		}
+		return result;
+	}
+
+	static size_t PageOwnerCount(TextureCache& cache, uint64_t address) {
+		std::lock_guard lock(cache.m_lock);
+		const auto*     owners = cache.m_image_page_table.Find(
+		    static_cast<size_t>(address >> TextureCache::ImagePageTable::kPageBits));
+		return owners == nullptr ? 0 : owners->size();
+	}
+
+	static size_t OwnedPageCount(TextureCache& cache, uint64_t address, uint64_t size, ImageId id) {
+		std::lock_guard                  lock(cache.m_lock);
+		TextureCache::ImagePageTable::PageRange pages {};
+		if (!TextureCache::ImagePageTable::TryGetPageRange(address, size, pages)) {
+			return 0;
+		}
+		size_t count = 0;
+		for (size_t page = pages.first; page < pages.last_exclusive; ++page) {
+			const auto* owners = cache.m_image_page_table.Find(page);
+			count += owners != nullptr && owners->Contains(id) ? 1 : 0;
+		}
+		return count;
+	}
+
+	static void AddPageOwner(TextureCache& cache, uint64_t address, ImageId id) {
+		std::lock_guard lock(cache.m_lock);
+		cache.m_image_page_table[static_cast<size_t>(
+		    address >> TextureCache::ImagePageTable::kPageBits)]
+		    .push_back(id);
+	}
+
+	static bool RemovePageOwner(TextureCache& cache, uint64_t address, ImageId id) {
+		std::lock_guard lock(cache.m_lock);
+		auto*           owners = cache.m_image_page_table.Find(
+		    static_cast<size_t>(address >> TextureCache::ImagePageTable::kPageBits));
+		return owners != nullptr && owners->Erase(id);
+	}
+
+	static void SetQueryEpoch(TextureCache& cache, uint32_t epoch) {
+		std::lock_guard lock(cache.m_lock);
+		cache.m_image_query_epoch = epoch;
+	}
+
+	static uint32_t QueryEpoch(TextureCache& cache) {
+		std::lock_guard lock(cache.m_lock);
+		return cache.m_image_query_epoch;
+	}
+
+	static ImageId InsertImage(TextureCache& cache, const ImageInfo& info) {
+		std::lock_guard transaction(cache.m_resource_mutex);
+		std::lock_guard lock(cache.m_lock);
+		return cache.InsertImage(info);
+	}
+
+	static void DeleteImage(TextureCache& cache, ImageId id) {
+		std::lock_guard transaction(cache.m_resource_mutex);
+		std::lock_guard lock(cache.m_lock);
+		cache.DeleteImage(id);
+	}
+
 	static std::shared_ptr<Image> Owner(const TextureCache& cache, ImageId id) {
 		return cache.ResolveOwner(id);
 	}
@@ -2488,6 +2561,110 @@ public:
 			                vk::Format::eR8G8B8A8Srgb,
 			        "registered compatible backing did not reuse one ImageId");
 
+			const auto IsOnlyImage = [](const std::vector<ImageId>& ids, ImageId expected) {
+				return ids.size() == 1 && ids.front() == expected;
+			};
+			const auto exact_byte_miss =
+			    TextureCacheTestAccess::FindImages(texture_cache, base + 8, 1, false);
+			const auto touched_page_hit =
+			    TextureCacheTestAccess::FindImages(texture_cache, base + 8, 1, true);
+			const auto next_page_miss =
+			    TextureCacheTestAccess::FindImages(texture_cache, base + 0x1000, 1, true);
+			Require(name, "exact and 4-KiB page filtering",
+			        exact_byte_miss.empty() && IsOnlyImage(touched_page_hit, first) &&
+			            next_page_miss.empty(),
+			        "coarse candidates did not preserve exact-byte and touched-page semantics");
+
+			const auto MakeOwnershipInfo = [](uint64_t address, uint64_t size) {
+				ImageInfo info {};
+				info.data      = {address, size};
+				info.extent    = {1, 1, 1};
+				info.resources = {1, 1};
+				info.samples   = 1;
+				return info;
+			};
+			const auto spanning_info = MakeOwnershipInfo(base + 0x1ff000, 0x2000);
+			const auto spanning = TextureCacheTestAccess::InsertImage(texture_cache, spanning_info);
+			const auto spanning_results = TextureCacheTestAccess::FindImages(
+			    texture_cache, spanning_info.data.address, spanning_info.data.size, false);
+			Require(name, "one-MiB cross-page deduplication",
+			        spanning && IsOnlyImage(spanning_results, spanning) &&
+			            TextureCacheTestAccess::PageOwnerCount(texture_cache,
+			                                                       spanning_info.data.address) == 1 &&
+			            TextureCacheTestAccess::PageOwnerCount(
+			                texture_cache, spanning_info.data.End() - 1) == 1,
+			        "an image spanning two coarse pages was missing or returned more than once");
+			TextureCacheTestAccess::DeleteImage(texture_cache, spanning);
+			Require(name, "cross-page owner cleanup",
+			        TextureCacheTestAccess::PageOwnerCount(texture_cache,
+			                                               spanning_info.data.address) == 0 &&
+			            TextureCacheTestAccess::PageOwnerCount(
+			                texture_cache, spanning_info.data.End() - 1) == 0 &&
+			            TextureCacheTestAccess::FindImages(texture_cache,
+			                                               spanning_info.data.address,
+			                                               spanning_info.data.size, false)
+			                .empty(),
+			        "cross-page unregister left a stale coarse-page membership");
+
+			const auto shared_info = MakeOwnershipInfo(base + 0x500100, 0x100);
+			const auto shared_first =
+			    TextureCacheTestAccess::InsertImage(texture_cache, shared_info);
+			const auto shared_second =
+			    TextureCacheTestAccess::InsertImage(texture_cache, shared_info);
+			const auto shared_results = TextureCacheTestAccess::FindImages(
+			    texture_cache, shared_info.data.address, shared_info.data.size, false);
+			Require(name, "shared coarse-page registration",
+			        shared_results.size() == 2 &&
+			            std::find(shared_results.begin(), shared_results.end(), shared_first) !=
+			                shared_results.end() &&
+			            std::find(shared_results.begin(), shared_results.end(), shared_second) !=
+			                shared_results.end(),
+			        "two registered owners were not retained in one coarse page");
+			TextureCacheTestAccess::DeleteImage(texture_cache, shared_first);
+			const auto shared_survivor = TextureCacheTestAccess::FindImages(
+			    texture_cache, shared_info.data.address, shared_info.data.size, false);
+			Require(name, "shared coarse-page unregister",
+			        IsOnlyImage(shared_survivor, shared_second) &&
+			            TextureCacheTestAccess::PageOwnerCount(texture_cache,
+			                                                       shared_info.data.address) == 1,
+			        "unregistering one owner removed its coarse-page neighbor");
+			TextureCacheTestAccess::DeleteImage(texture_cache, shared_second);
+			Require(name, "final shared coarse-page unregister",
+			        TextureCacheTestAccess::PageOwnerCount(texture_cache,
+			                                               shared_info.data.address) == 0,
+			        "the final shared owner remained registered");
+
+			constexpr uint64_t large_owner_size = 64ull * 1024 * 1024;
+			const auto large_info = MakeOwnershipInfo(base + 0x800000, large_owner_size);
+			const auto large_owner =
+			    TextureCacheTestAccess::InsertImage(texture_cache, large_info);
+			Require(name, "production one-MiB registration granularity",
+			        TextureCacheTestAccess::OwnedPageCount(
+			            texture_cache, large_info.data.address, large_info.data.size, large_owner) == 64,
+			        "64 MiB image registration did not create exactly 64 coarse memberships");
+			TextureCacheTestAccess::DeleteImage(texture_cache, large_owner);
+			Require(name, "production one-MiB unregister granularity",
+			        TextureCacheTestAccess::OwnedPageCount(
+			            texture_cache, large_info.data.address, large_info.data.size, large_owner) == 0,
+			        "large image unregister left coarse memberships behind");
+
+			const ImageId stale {first.index, first.generation + 1};
+			TextureCacheTestAccess::AddPageOwner(texture_cache, base, stale);
+			const auto stale_filtered =
+			    TextureCacheTestAccess::FindImages(texture_cache, base, sizeof(initial), false);
+			Require(name, "stale page owner filtering",
+			        IsOnlyImage(stale_filtered, first) &&
+			            TextureCacheTestAccess::RemovePageOwner(texture_cache, base, stale),
+			        "a stale generation escaped the direct page-owner lookup");
+
+			TextureCacheTestAccess::SetQueryEpoch(texture_cache, UINT32_MAX);
+			const auto wrap_results =
+			    TextureCacheTestAccess::FindImages(texture_cache, base, sizeof(initial), false);
+			Require(name, "page-owner query epoch wrap",
+			        IsOnlyImage(wrap_results, first) &&
+			            TextureCacheTestAccess::QueryEpoch(texture_cache) == 1,
+			        "query deduplication failed while wrapping its epoch");
+
 			auto&              image               = texture_cache.GetImage(first);
 			constexpr uint32_t final_sampled_value = 0x88776655u;
 			Require(name, "sampled write between discovery and acquisition",