Re: Crippling change in ld memory/cpu consumption in v2.12/v2.13

[Robert D. Kennedy]

Hello,

        Thank you for your suggestions.

        Short answer, yes we still see the memory increase with those switches. 
I 
retried --no-keep-memory and tried -z recombreloc, together and separately. 
--no-keep memory decreases memory use by a few MB and increases link time by a 
few seconds. -z recombreloc does not seem to have any substantial effect on 
cpu/memory use. I tried these with 2.11.93 (RHL 7.3) and v2.13 (dist tarball).

        I am using the same updated "native" gcc from RedHat Linux 7.3 in each 
of 
these cases, from RPM gcc-2.96-112. We have tested also older linkers with 
older GNU C compilers, but realized this left open the possibility that ABI 
changes or some such were involved, and chose to vary only the linker version.

        My colleagues are working now on a script that auto-generates source to 
produce libraries and executables of widely varying size and content so that 
this effect can be studied and reproduced elsewhere.

Thanks,
Rob Kennedy
Fermi National Accelerator Laboratory
Computing Division - CDF Computing and Analysis


> On Wed, Sep 11, 2002 at 12:53:21PM -0500, Robert D. Kennedy wrote:
> > On a Red Hat Linux 7.3 PC, the memory increased by 
> > about a factor of 3 between v2.11.2 and v2.12 to link the same 65 MB 
> > executable.
> 
> Are you exactly the same compiler when comparing different versions of
> ld?  Newer gcc's will use new features of ld, like the string merge
> capability.  You'll pay some penalty in mem usage for these features.
> 
> Do you see the same sort of memory increase if you use --no-keep-memory?
> Try -z nocombreloc too.
> 
> -- 
> Alan Modra
> IBM OzLabs - Linux Technology Centre