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The effect of TCmalloc in the QtWebKit port - stage 1: Performance
Much time has passed since we started to work on the custom allocation framework with Paul Pedriana. The core of the solution (FastAllocBase class, bug #20422) was landed into the trunk half year ago. After that check in we started to work on JavaScriptCore class inheritances, because every class which is instantiated by operator new needs to be inherited from FastAllocBase. Now, after that half year, almost every necessary class in JavaScriptCore is inherited from FastAllocBase. These changes made the enabling of TCmalloc on Qt-related WebKit ports possible.
Results for x86
Let's see the speed results of QtWebKit on x86-Linux (with JIT) in the following table:
Results for ARM
We do benchmarking on ARM hardware as well. The effect of enabling TCmalloc on ARM (with JIT) is as follows:
FutureThe integration of the custom allocation framework for WebCore is still in progress, so I can not show performance results for the whole WebKit yet. After all... As the charts show, we achieved effective performance improvement with enabling TCmalloc on the Qt-port of WebKit. However, there is always a reverse of a medal... I'll talk about the memory costs in another post. :-) |
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Anonymous (not verified) - 10/08/2009 - 21:08
Do the performance gains justify taking on the maintenance of something that's provided natively by the system, as well as the memory costs you hint at?
akos.kiss - 10/08/2009 - 21:23
The memory cost is not that of the solution but comes from TCmalloc itself. So, if you use the custom allocation framework to use VeryMemoryFriendlyMalloc instead of TCmalloc or the system allocator, then you will observe a drop in memory consumption. Well, but then there will be a reverse of the medal, too... (i.e., performance loss).
The key is that now you are *able* to choose which allocator you want to use. And this is *not* provided by the system. At least not on Qt Linux platforms. As far as I remember, the background is described in the bug report referenced in the blog post.
Anonymous (not verified) - 10/09/2009 - 12:16
Hi,
What about other allocators, like jemalloc :-?
akos.kiss - 10/09/2009 - 12:48
Actually, JEmalloc is quite in our focus. That topic will be covered in another post. (First, it was easier for us to work with TCmalloc since it is already a part of WebKit - see http://trac.webkit.org/browser/trunk/JavaScriptCore/wtf/FastMalloc.cpp )
quickembed (not verified) - 05/15/2012 - 16:35
arm embedded system R&D
we are porting qt webkit v8 to arm linux
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