Re: The cost of stack traces

[David Daney <ddaney at avtrex dot com>]

Casey Marshall wrote:
> Something I wanted to do in the DWARF reader I wrote (but never did,  
> since the patch wasn't accepted) was to cache *approximate*  information 
> about where to look for debug info for an address. So  you'd have a 
> range of PC values that would map to regions in  the .debug_line section 
> where you would find the debug info you were  looking for. That would 
> probably help lookup times, at least in a  long-running application, and 
> the map wouldn't need to contain too  much data.
>
> The big slowdown, from what I can tell, is that you have to scan from  
> the very beginning of the debug info to find the address, and that  can 
> be slow for huge libraries like libgcj. You could probably  optimize the 
> hell out of this, by scanning a library just once and  building a good, 
> approximate cache of where to look things up.
>
> Shall I post my patch for this again? :-)

I, for one, would like very much to see the patch again.

What were the reasons that it was not accepted?

David Daney