Changeset 178183 in webkit

Timestamp:

Jan 9, 2015 12:07:17 PM (9 years ago)

Author:

akling@apple.com

Message:

[Cocoa] Make decoded image data purgeable ASAP.
<​https://webkit.org/b/140298>

Reviewed by Antti Koivisto.

Mark decoded images as "transient" which makes CoreGraphics mark
the backing stores as purgeable shortly after they're used.

The decoded representation will remain in CoreGraphics's caches
indefinitely unless the kernel gets starved and needs the pages.

Most resources will now reach a state where the encoded data is
mmap'ed from disk cache (once the entire resource is downloaded)
and the decoded data is purgeable.

This also has the side effect of making the MemoryCache more
palatial since the decoded data cost can be deducted for images,
allowing us to cache more resources.

Note that the worst case for this new behavior would be something
like hovering below 100% memory utilization and constantly having
to drop and re-decode images. While churny, it still beats
crashing the process, plus there's tiling to remove many of the
reasons we'd need the decoded data.

• platform/graphics/cg/ImageSourceCG.cpp:

(WebCore::ImageSource::createFrameAtIndex):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/cg/ImageSourceCG.cpp (modified) (2 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2015-01-09  Andreas Kling  <akling@apple.com>
+
+        [Cocoa] Make decoded image data purgeable ASAP.
+        <https://webkit.org/b/140298>
+
+        Reviewed by Antti Koivisto.
+
+        Mark decoded images as "transient" which makes CoreGraphics mark
+        the backing stores as purgeable shortly after they're used.
+
+        The decoded representation will remain in CoreGraphics's caches
+        indefinitely unless the kernel gets starved and needs the pages.
+
+        Most resources will now reach a state where the encoded data is
+        mmap'ed from disk cache (once the entire resource is downloaded)
+        and the decoded data is purgeable.
+
+        This also has the side effect of making the MemoryCache more
+        palatial since the decoded data cost can be deducted for images,
+        allowing us to cache more resources.
+
+        Note that the worst case for this new behavior would be something
+        like hovering below 100% memory utilization and constantly having
+        to drop and re-decode images. While churny, it still beats
+        crashing the process, plus there's tiling to remove many of the
+        reasons we'd need the decoded data.
+
+        * platform/graphics/cg/ImageSourceCG.cpp:
+        (WebCore::ImageSource::createFrameAtIndex):
+
 2015-01-09  Gwang Yoon Hwang  <yoon@igalia.com>
 

trunk/Source/WebCore/platform/graphics/cg/ImageSourceCG.cpp

@@ -348 +348 @@
     RetainPtr<CGImageRef> image = adoptCF(CGImageSourceCreateImageAtIndex(m_decoder, index, imageSourceOptions(subsamplingLevel).get()));
 
-#if PLATFORM(IOS)
-    // <rdar://problem/7371198> - CoreGraphics changed the default caching behaviour in iOS 4.0 to kCGImageCachingTransient
-    // which caused a performance regression for us since the images had to be resampled/recreated every time we called
-    // CGContextDrawImage. We now tell CG to cache the drawn images. See also <rdar://problem/14366755> -
-    // CoreGraphics needs to un-deprecate kCGImageCachingTemporary since it's still not the default.
-#if COMPILER(CLANG)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdeprecated-declarations"
-#endif
-    CGImageSetCachingFlags(image.get(), kCGImageCachingTemporary);
-#if COMPILER(CLANG)
-#pragma clang diagnostic pop
-#endif
-#endif // PLATFORM(IOS)
+    CGImageSetCachingFlags(image.get(), kCGImageCachingTransient);
 
     CFStringRef imageUTI = CGImageSourceGetType(m_decoder);
@@ -368 +355 @@
     if (!imageUTI)
         return image.leakRef();
-
-#if PLATFORM(MAC) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101000
-    if (CFEqual(imageUTI, kUTTypeGIF)) {
-        CGImageSetCachingFlags(image.get(), kCGImageCachingTransient);
-        return image.leakRef();
-    }
-#endif
 
     if (!CFEqual(imageUTI, xbmUTI))