[Lldb-commits] [lldb] r105834 - in /lldb/trunk: include/lldb/Symbol/Symtab.h source/Symbol/Symtab.cpp

[Owen Anderson]

OK, I just performed these measurements on 64-bit 10.6, with both -Os and -O3 builds of lldb.  In both cases, std::sort was on the order of 50% slower than qsort_r:

                   -Os      -O3
std::sort          0.118s   0.103s       
qsort_r            0.077s   0.078s

However, here's the interesting part:

std::stable_sort   0.051s   0.048s

So, it looks like the symbol tables are already mostly sorted, and a simple insertion sort is able to "complete" the sort quickly.  FWIW, this would also be a good place to apply TimSort or some other heuristic sort.

--Owen


On Jun 16, 2010, at 9:27 AM, Greg Clayton wrote:

> We start with "Sketch" from the /Developer/Expamples. It loads 91 shared libraries right off the bat, and if you then type:
> 
> (lldb) log timers enable
> (lldb) breakpoint set --name main
> (lldb) log timers disable
> 
> All of the symbol tables will be pulled in, and it will dump the timing information. 
> 
> You will first need to add a scoped timer to the top of:
> 
> Symtab::SortSymbolIndexesByValue()
> 
> The easiest way is:
> 
>     Timer scoped_timer (__PRETTY_FUNCTION__,__PRETTY_FUNCTION__);
> 
> Then you should see an entry in the timer dump for Symtab::SortSymbolIndexesByValue when the "log timers disable" is run with a total time.
> 


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/lldb-commits/attachments/20100616/d3c7a7f6/attachment.html>