Re: [PATCH 1/4] stringbuf: A string buffer implementation

Matt Mackall
2007-10-26T20:57:49Z

On Fri, Oct 26, 2007 at 05:57:27AM -0600, Matthew Wilcox wrote:
> On Fri, Oct 26, 2007 at 12:11:01PM +1000, Rusty Russell wrote:
> > This just seems like more optimization and complexity that we need. Interfaces
> > using vsnprintf don't seem like good candidates for optimization.
>
> That's a fair point, but I'm optimising for fewer trips into the
> slab(/slub/slob) allocator, and thus having less of an impact on the
> rest of the system. Given that 'an alloc on every call' was one of the
> complaints Matt had about my v1 stringbuf patch, I can't imagine he'll
> be happy about this one either.

Well I expect once you start letting people easily build strings by
concatenation, you'll very shortly afterwards have people using them
in loops. And having hidden O(n^2) behavior in there is a little sad,
even though n will tend to be small and well-bounded. If we can do
something simple to avoid it, we should.

--
Mathematics is the supreme nostalgia of our time.