From 5bc972a4118927be7d2b81e4ff66be5bc274fdaa Mon Sep 17 00:00:00 2001
From: Laszlo Agocs <laszlo.agocs@qt.io>
Date: Tue, 1 Oct 2019 14:36:29 +0200
Subject: [PATCH] rhi: vulkan: Disable vkmemalloc's own synchronization
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No need for those mutexes.

Task-number: QTBUG-78908
Change-Id: I60c32df1f8729098f1894eff7c71e7fbcbd23ecf
Reviewed-by: Christian Strømme <christian.stromme@qt.io>
---
 src/gui/rhi/qrhivulkan.cpp | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/gui/rhi/qrhivulkan.cpp b/src/gui/rhi/qrhivulkan.cpp
index 3a2c35b589..c7d28a4f18 100644
--- a/src/gui/rhi/qrhivulkan.cpp
+++ b/src/gui/rhi/qrhivulkan.cpp
@@ -568,6 +568,9 @@ bool QRhiVulkan::create(QRhi::Flags flags)
 
         VmaAllocatorCreateInfo allocatorInfo;
         memset(&allocatorInfo, 0, sizeof(allocatorInfo));
+        // A QRhi is supposed to be used from one single thread only. Disable
+        // the allocator's own mutexes. This gives a performance boost.
+        allocatorInfo.flags = VMA_ALLOCATOR_CREATE_EXTERNALLY_SYNCHRONIZED_BIT;
         allocatorInfo.physicalDevice = physDev;
         allocatorInfo.device = dev;
         allocatorInfo.pVulkanFunctions = &afuncs;