[Lldb-commits] [PATCH] D122975: parallelize module loading in DynamicLoaderPOSIXDYLD()

[Luboš Luňák via Phabricator via lldb-commits]

llunak added a comment.

In D122975#3426575 <https://reviews.llvm.org/D122975#3426575>, @labath wrote:

> I'd like to understand what is the precise thing that you're trying to optimise. If there is like a single hot piece of code that we want to optimise, then we might be able to come up with an different approach (a'la PrefetchModuleSpecs) to achieve the same thing.

F22668124: lldb2.png <https://reviews.llvm.org/F22668124>

The scenario is a repeated lldb start with index cache enabled (and so everything necessary cached), the debugged app is debug build of LibreOffice Calc (~100 medium-sized C++ libraries). 90% of the CPU time is spent in LoadFromCache() calls, because 70% of the CPU time is spent in ConstString (and that's after my ConstString optimizations). I don't think there's any other way to make it faster other than parallelizing it, although parallelizing only LoadFromCache() should be enough and I'd expect that to be limited enough to be safe if you expect the lldb codebase is not generally thread-safe. In this patch I parallelized higher because it was simple to do it up there, and I don't know how to easily get at all the LoadFromCache() calls (especially the one called from SymbolFileDWARFDebugMap is relatively deep). If you know how to parallelize only that, that works for me too.


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https://reviews.llvm.org/D122975