From 26916692835ee03a8600c5236b0b7de9cf1d55b6 Mon Sep 17 00:00:00 2001
From: vinsentli <vinsentli@tencent.com>
Date: Sat, 10 Jan 2026 10:21:01 +0800
Subject: [PATCH 1/2] igl | vulkan | Reuse the cached VkDescriptorSet to reduce
 vkAllocateDescriptorSets().

---
 src/igl/vulkan/VulkanContext.cpp | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/src/igl/vulkan/VulkanContext.cpp b/src/igl/vulkan/VulkanContext.cpp
index 07ddc9955f..31b345f815 100644
--- a/src/igl/vulkan/VulkanContext.cpp
+++ b/src/igl/vulkan/VulkanContext.cpp
@@ -249,7 +249,12 @@ class DescriptorPoolsArena final {
     if (!numRemainingDSetsInPool_) {
       switchToNewDescriptorPool(ic, nextSubmitHandle);
     }
-    VK_ASSERT(ivkAllocateDescriptorSet(&ctx_.vf_, device_, pool_, dsl_, &dset));
+    if (isNewPool_) {
+      VK_ASSERT(ivkAllocateDescriptorSet(&ctx_.vf_, device_, pool_, dsl_, &dset));
+      allocedDSet_.emplace_back(dset);
+    } else {
+      dset = allocedDSet_[dsetCursor_++];
+    }
     numRemainingDSetsInPool_--;
     return dset;
   }
@@ -260,7 +265,7 @@ class DescriptorPoolsArena final {
     numRemainingDSetsInPool_ = kNumDSetsPerPool;
 
     if (pool_ != VK_NULL_HANDLE) {
-      extinct_.push_back({pool_, nextSubmitHandle});
+      extinct_.push_back({pool_, nextSubmitHandle, allocedDSet_});
     }
     // first, let's try to reuse the oldest extinct pool (never reuse pools that are tagged with the
     // same SubmitHandle because they have not yet been submitted)
@@ -268,8 +273,10 @@ class DescriptorPoolsArena final {
       const ExtinctDescriptorPool p = extinct_.front();
       if (ic.isReady(p.handle)) {
         pool_ = p.pool;
+        allocedDSet_ = p.allocedDSet;
+        dsetCursor_ = 0;
+        isNewPool_ = false;
         extinct_.pop_front();
-        VK_ASSERT(ctx_.vf_.vkResetDescriptorPool(device_, pool_, VkDescriptorPoolResetFlags{}));
         return;
       }
     }
@@ -288,6 +295,9 @@ class DescriptorPoolsArena final {
                                       &pool_));
     VK_ASSERT(ivkSetDebugObjectName(
         &ctx_.vf_, device_, VK_OBJECT_TYPE_DESCRIPTOR_POOL, (uint64_t)pool_, dpDebugName_.c_str()));
+    allocedDSet_.clear();
+    dsetCursor_ = 0;
+    isNewPool_ = true;
   }
 
  private:
@@ -296,6 +306,9 @@ class DescriptorPoolsArena final {
   const VulkanContext& ctx_;
   VkDevice device_ = VK_NULL_HANDLE;
   VkDescriptorPool pool_ = VK_NULL_HANDLE;
+  uint32_t dsetCursor_ = 0;
+  std::vector<VkDescriptorSet> allocedDSet_;
+  bool isNewPool_ = true; //is a new created pool or an old cached pool
   const uint32_t numTypes_ = 0;
   VkDescriptorType types_[2] = {VK_DESCRIPTOR_TYPE_MAX_ENUM, VK_DESCRIPTOR_TYPE_MAX_ENUM};
   const uint32_t numDescriptorsPerDSet_ = 0;
@@ -307,6 +320,7 @@ class DescriptorPoolsArena final {
   struct ExtinctDescriptorPool {
     VkDescriptorPool pool = VK_NULL_HANDLE;
     VulkanImmediateCommands::SubmitHandle handle = {};
+    std::vector<VkDescriptorSet> allocedDSet;
   };
 
   std::deque<ExtinctDescriptorPool> extinct_;

From 5bd8ab5c8280fd96a4a43a5c692df44db66cba24 Mon Sep 17 00:00:00 2001
From: vinsentli <vinsentli@tencent.com>
Date: Sat, 10 Jan 2026 21:55:16 +0800
Subject: [PATCH 2/2] code review

---
 src/igl/vulkan/VulkanContext.cpp | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/igl/vulkan/VulkanContext.cpp b/src/igl/vulkan/VulkanContext.cpp
index 31b345f815..13e6873b3f 100644
--- a/src/igl/vulkan/VulkanContext.cpp
+++ b/src/igl/vulkan/VulkanContext.cpp
@@ -251,9 +251,9 @@ class DescriptorPoolsArena final {
     }
     if (isNewPool_) {
       VK_ASSERT(ivkAllocateDescriptorSet(&ctx_.vf_, device_, pool_, dsl_, &dset));
-      allocedDSet_.emplace_back(dset);
+      allocatedDSet_.emplace_back(dset);
     } else {
-      dset = allocedDSet_[dsetCursor_++];
+      dset = allocatedDSet_[dsetCursor_++];
     }
     numRemainingDSetsInPool_--;
     return dset;
@@ -265,7 +265,7 @@ class DescriptorPoolsArena final {
     numRemainingDSetsInPool_ = kNumDSetsPerPool;
 
     if (pool_ != VK_NULL_HANDLE) {
-      extinct_.push_back({pool_, nextSubmitHandle, allocedDSet_});
+      extinct_.push_back({pool_, nextSubmitHandle, allocatedDSet_});
     }
     // first, let's try to reuse the oldest extinct pool (never reuse pools that are tagged with the
     // same SubmitHandle because they have not yet been submitted)
@@ -273,7 +273,7 @@ class DescriptorPoolsArena final {
       const ExtinctDescriptorPool p = extinct_.front();
       if (ic.isReady(p.handle)) {
         pool_ = p.pool;
-        allocedDSet_ = p.allocedDSet;
+        allocatedDSet_ = p.allocatedDSet;
         dsetCursor_ = 0;
         isNewPool_ = false;
         extinct_.pop_front();
@@ -295,7 +295,7 @@ class DescriptorPoolsArena final {
                                       &pool_));
     VK_ASSERT(ivkSetDebugObjectName(
         &ctx_.vf_, device_, VK_OBJECT_TYPE_DESCRIPTOR_POOL, (uint64_t)pool_, dpDebugName_.c_str()));
-    allocedDSet_.clear();
+    allocatedDSet_.clear();
     dsetCursor_ = 0;
     isNewPool_ = true;
   }
@@ -307,8 +307,8 @@ class DescriptorPoolsArena final {
   VkDevice device_ = VK_NULL_HANDLE;
   VkDescriptorPool pool_ = VK_NULL_HANDLE;
   uint32_t dsetCursor_ = 0;
-  std::vector<VkDescriptorSet> allocedDSet_;
-  bool isNewPool_ = true; //is a new created pool or an old cached pool
+  std::vector<VkDescriptorSet> allocatedDSet_;
+  bool isNewPool_ = true; // is a new created pool or an old cached pool
   const uint32_t numTypes_ = 0;
   VkDescriptorType types_[2] = {VK_DESCRIPTOR_TYPE_MAX_ENUM, VK_DESCRIPTOR_TYPE_MAX_ENUM};
   const uint32_t numDescriptorsPerDSet_ = 0;
@@ -320,7 +320,7 @@ class DescriptorPoolsArena final {
   struct ExtinctDescriptorPool {
     VkDescriptorPool pool = VK_NULL_HANDLE;
     VulkanImmediateCommands::SubmitHandle handle = {};
-    std::vector<VkDescriptorSet> allocedDSet;
+    std::vector<VkDescriptorSet> allocatedDSet;
   };
 
   std::deque<ExtinctDescriptorPool> extinct_;