[Bug 1463] New: poor performance with large block size

[Wayne Davison]

On Fri, Jul 16, 2004 at 08:20:51PM -0400, Chris Shoemaker wrote:
> On Thu, Jul 15, 2004 at 07:06:28PM -0700, Wayne Davison wrote:
> > +	max_map_size = MIN(MAX_MAP_SIZE, blength * 32);
> 
> This makes max_map_size a multiple (32) of blength
> for a large range  (blength*32 < MAX_MAP_SIZE),

Oops, that was supposed to be MAX(), not MIN(), otherwise it doesn't
help the problem of too-many memory moves for large block sizes.  I'll
go ahead and check that change in for now and look forward to your
findings on improving the code.

> ISTM, that the only reason to have the slight lag in window
> advancement is you expected to frequently service requests where the
> offset was decreasing just a little.  I didn't see that happening
> anywhere.  Did I miss something?

I think the only place where the calls might not advance are in the
receiver where the map_ptr() calls can be to any block-size-multiple
in the basis file.  It seems strange to me to force a 256K read for
every basis-file match, so maybe this is something else to look into
optimizing.

..wayne..