Re: dpkg

[Adam Heath <doogie@debian.org>]

On Fri, 30 Mar 2001, Joey Hess wrote:

> I've been running (testing's) dpkg on a low memory 486/33 a lot lately.
> Poor me. Anyway, it seems to take dpkg about 5 minutes to print
> *anything*, then in relatively short order, it reads the database, and
> is off to installing the package.
>
> I straced it during the mysterious pause, and find it is reading what
> looks like the available file, one 16k block at a time, with each block
> taking almost 1 second to read on my 486.
>
> It's a 486, but it shouldn't be that slow. Is this a known performance
> problem, or should I look into it?

Please try dpkg from cvs.  What you are seeing is dpkg using libc's getc()
function, which has an internal buffer of 16k.  In cvs, I read the entire file
at once into a buffer of the right size, or I mmap it(defaults to the former,
and is only changable with a #define).

The speedup on my dual-celeron 333 was 20-35%.  I can see slower machines
getting a bigger boost.