[PATCH] libdw: add thread-safety to dwarf_getabbrev()

Florian Weimer fw@deneb.enyo.de
Sat Oct 26 16:50:00 GMT 2019


* Jonathon Anderson:

>> This assumes that memory allocation
>> is actually a performance problem, otherwise you could let malloc
>> handle the details.
>
> In our (Dyninst + HPCToolkit) work, we have found that malloc tends to 
> be slow in the multithreaded case, in particular with many small 
> allocations. The glibc implementation (which most of our clients use) 
> uses a full mutex to provide thread-safety. While we could do a lot 
> better in our own projects with regards to memory management, the fact 
> remains that malloc alone is a notable facet to the performance of 
> libdw.

Current glibc versions have a thread-local fast path, which should
address some of these concerns.  It's still not a bump-pointer
allocator, but at least there are no atomics on that path.

I'm not sure if it is prudent to code around imperfections in older
allocators.



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