On Tue, 10 Jun 2008 19:40:22 +0530
"Arun Raghavan" <arunisgod@...> wrote:
> On Tue, Jun 10, 2008 at 7:32 PM, Ciaran McCreesh
> <ciaran.mccreesh@...> wrote:
> [...]
> >> I don't think that filename-vs-first-line is going to make a big
> >> difference in practical performance.
> >
> > It's about a factor of five difference in cold-cache resolution
> > performance for Paludis.
> 
> Could you please share more details on the experiment that showed this
> kind of performance degradation and the numbers, if possible?

Shove an open and a getline in when doing what would otherwise be a
successful cache read. It adds a couple of thousand new open()s on
files that would otherwise be left alone, and changes the nice linear
"slurp up things in this directory in order until we don't need
anything else" pattern into "bounce backwards and forwards between lots
of files in two different directories".

On a cold cache, which is the most common use case, this is very very
nasty.

-- 
Ciaran McCreesh