4 files changed, 38 insertions, 4 deletions
diff --git a/indra/newview/app_settings/settings.xml b/indra/newview/app_settings/settings.xml
index 1ea08498c5..f0ba6eff95 100644
--- a/indra/newview/app_settings/settings.xml
+++ b/indra/newview/app_settings/settings.xml
@@ -7808,7 +7808,18 @@
   <key>RenderLowMemMinDiscardIncrement</key>
   <map>
     <key>Comment</key>
-    <string>Minimum increment of discard level if system memory gets low</string>
+    <string>Minimum increment of discard bias if available texture memory gets low</string>
+    <key>Persist</key>
+    <integer>1</integer>
+    <key>Type</key>
+    <string>F32</string>
+    <key>Value</key>
+    <real>0.1</real>
+  </map>
+  <key>RenderHighMemMinDiscardDecrement</key>
+  <map>
+    <key>Comment</key>
+    <string>Minimum decrement of discard bias if excess texture memory is available</string>
     <key>Persist</key>
     <integer>1</integer>
     <key>Type</key>
diff --git a/indra/newview/lltexturefetch.cpp b/indra/newview/lltexturefetch.cpp
index 703030b978..bac0c736b1 100644
--- a/indra/newview/lltexturefetch.cpp
+++ b/indra/newview/lltexturefetch.cpp
@@ -1761,7 +1761,10 @@ bool LLTextureFetchWorker::doWork(S32 param)
         mRawImage = NULL;
         mAuxImage = NULL;
         llassert_always(mFormattedImage.notNull());
-        S32 discard = mHaveAllData ? 0 : mLoadedDiscard;
+
+        // if we have the entire image data (and the image is not J2C), decode the full res image
+        // DO NOT decode a higher res j2c than was requested.  This is a waste of time and memory.
+        S32 discard = mHaveAllData && mFormattedImage->getCodec() != IMG_CODEC_J2C ? 0 : mLoadedDiscard;
         mDecoded  = false;
         setState(DECODE_IMAGE_UPDATE);
         LL_DEBUGS(LOG_TXT) << mID << ": Decoding. Bytes: " << mFormattedImage->getDataSize() << " Discard: " << discard
@@ -2318,6 +2321,10 @@ void LLTextureFetchWorker::callbackDecoded(bool success, const std::string &erro
         mRawImage = raw;
         mAuxImage = aux;
         mDecodedDiscard = mFormattedImage->getDiscardLevel();
+        if (mDecodedDiscard < mDesiredDiscard)
+        {
+            LL_WARNS_ONCE(LOG_TXT) << "Decoded higher resolution than requested" << LL_ENDL;
+        }
         LL_DEBUGS(LOG_TXT) << mID << ": Decode Finished. Discard: " << mDecodedDiscard
                            << " Raw Image: " << llformat("%dx%d",mRawImage->getWidth(),mRawImage->getHeight()) << LL_ENDL;
     }
diff --git a/indra/newview/llviewertexture.cpp b/indra/newview/llviewertexture.cpp
index e14ddc4360..14647d6f84 100644
--- a/indra/newview/llviewertexture.cpp
+++ b/indra/newview/llviewertexture.cpp
@@ -559,7 +559,10 @@ void LLViewerTexture::updateClass()
         // lower discard bias over time when free memory is available
         if (sDesiredDiscardBias > 1.f && over_pct < 0.f)
         {
-            sDesiredDiscardBias -= gFrameIntervalSeconds * 0.01f;
+            static LLCachedControl<F32> high_mem_discard_decrement(gSavedSettings, "RenderHighMemMinDiscardDecrement", .1f);
+
+            F32 decrement = high_mem_discard_decrement - llmin(over_pct, 0.f);
+            sDesiredDiscardBias -= decrement * gFrameIntervalSeconds;
         }
     }
 
diff --git a/indra/newview/llviewertexturelist.cpp b/indra/newview/llviewertexturelist.cpp
index b44bedea50..0b79c2d8e0 100644
--- a/indra/newview/llviewertexturelist.cpp
+++ b/indra/newview/llviewertexturelist.cpp
@@ -1066,13 +1066,26 @@ F32 LLViewerTextureList::updateImagesCreateTextures(F32 max_time)
     {
         LLViewerFetchedTexture* imagep = mCreateTextureList.front();
         llassert(imagep->mCreatePending);
-        imagep->createTexture();
+
+        // desired discard may change while an image is being decoded. If the texture in VRAM is sufficient
+        // for the current desired discard level, skip the texture creation.  This happens more often than it probably
+        // should
+        bool redundant_load = imagep->hasGLTexture() && imagep->getDiscardLevel() <= imagep->getDesiredDiscardLevel();
+
+        if (!redundant_load)
+        {
+           imagep->createTexture();
+        }
+
         imagep->postCreateTexture();
         imagep->mCreatePending = false;
         mCreateTextureList.pop();
 
         if (imagep->hasGLTexture() && imagep->getDiscardLevel() < imagep->getDesiredDiscardLevel())
         {
+            // NOTE: this may happen if the desired discard reduces while a decode is in progress and does not
+            // necessarily indicate a problem, but if log occurrences excede that of dsiplay_stats: FPS,
+            // something has probably gone wrong.
             LL_WARNS_ONCE("Texture") << "Texture will be downscaled immediately after loading." << LL_ENDL;
             imagep->scaleDown();
         }