Bug 201157 – [FTW] Use DirectX SharedResource as basis for SharedBitmap

• Status: RESOLVED
• Resolution: FIXED
• Component: WebKit2

[Brent Fulgham]

Currently an ID2D1Bitmap is used as the backing store for the SharedBitmap used to share data between the WebContent Process and the UIProcess. However, this involves moving GPU memory to local memory, copying the memory into the Shared Memory in the SharedBitmap, then building a new GPU bitmap on the UIProcess side from the shared memory store.

Profiling indicates that this is the single largest place WebKit spends its time.

Instead, we should use Direct2D's ability to render to an IDXGISurface, which can be shared between multiple processes. This should avoid the GPU->CPU copy, the Direct2D-allocated CPU->Shared Memory copy, and the shared memory to GPU copy.

[Brent Fulgham]

With this change:

After Bug 201122 I measured:

> AppleWin                  4.35
> WinCairo                  8.39
> FTW                      28.71

After these changes:

  FTW                      71.42

[Brent Fulgham]

Created attachment 377681 [details]
Patch

[Alex Christensen]

Comment on attachment 377681 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=377681&action=review

> Source/WebKit/Platform/SharedMemory.h:83
> +        static bool decodeHandle(IPC::Decoder&, HANDLE&);

Could you make this return Optional<HANDLE>?

> Source/WebKit/Shared/win/ShareableBitmapDirect2D.cpp:60
> +bool ShareableBitmap::Configuration::decodeSharedResourceHandle(IPC::Decoder& decoder)

These wrappers seem a bit excessive.  This code looks like it just belongs in the call site.

[Brent Fulgham]

Comment on attachment 377681 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=377681&action=review

>> Source/WebKit/Platform/SharedMemory.h:83
>> +        static bool decodeHandle(IPC::Decoder&, HANDLE&);
> 
> Could you make this return Optional<HANDLE>?

Sure!

>> Source/WebKit/Shared/win/ShareableBitmapDirect2D.cpp:60
>> +bool ShareableBitmap::Configuration::decodeSharedResourceHandle(IPC::Decoder& decoder)
> 
> These wrappers seem a bit excessive.  This code looks like it just belongs in the call site.

Okay. When I started I was trying to minimize changes to ShareableBItmap.cpp, but I ended up tweaking them anyway. I'lll move these lines.

[Brent Fulgham]

Created attachment 377729 [details]
Patch for landing

[WebKit Commit Bot]

Comment on attachment 377729 [details]
Patch for landing

Clearing flags on attachment: 377729

Committed r249335: <https://trac.webkit.org/changeset/249335>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Radar WebKit Bug Importer]

<rdar://problem/54889576>