Eric Bollengier <eric.bolleng...@baculasystems.com> wrote on 2010/08/08
18:52:03:
>
> Hello Joakim,
>
> On 20/07/2010 20:02, Joakim Tjernlund wrote:
> > This is a strait port of the Linux kernel crc32 optimization
> > I did a while ago. This impl. is several times faster than the one it
> > replaces. Adapted to bacula usage.
> > ---
> >
> > I have not tested this yet as I went/is on vacation but I figured
> > perhaps someone else is interrested enough to do that :)
> >
>
> I did some tests with a little crc32 program, and over a 9MB file, the cpu
> gain is about 33% and crc32 results seems to be identical (tested over
> 650MB by
> chunks of 5000 bytes).
>
> Thanks, this is a very nice contribution, and it will be included in the
> next stable community release.
Thanks for testing. I would have expected better performance though.
Are you by any chance using gcc 4.3.4? I have found this compiler
rather broken w.r.t optimization. For crc32 it was better to compile
with -Os than -O2. Kern has an updated version which has some
unrolling too, perhaps this one does better? Does you test program
include I/O too?
Jocke
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