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Re: DW_AT_specification and partial symtabs
On Fri, Jun 13, 2003 at 12:23:53PM -0400, Andrew Cagney wrote:
> >On Fri, Jun 13, 2003 at 11:38:38AM -0400, Andrew Cagney wrote:
> >
> >>Daniel wrote:
> >>
> >>
> >
> >>> > 1) is very easy to measure. GDB has a command line option --readnow
> >>> > which forces symtabs to be read in immediately. I tried my normal
> >>> > performance testcase: a dummy main() linked to all of mozilla's
> >>> > component libraries, with full stabs debug info. Note stabs, not
> >>> > DWARF2, so the timing may vary. Also note that we duplicate psymtab
> >>> > and symtab creation doing it this way, so it overestimates the cost.
> >
> >>
> >>I think that's an understatement.
> >
> >
> >Not really. You can subtract the psymtab time from the combined time,
> >and then compare. It still more than triples the time.
>
> So we agree, 25% is significant but 3% is not.
>
> A better question is what % of symtabs get draged in by a C++ `break
> main; run'. Wasn't the original conjecture that symtabs get sucked in
> anyway so why do it twice.
I am pretty sure that the conjecture is false. I've fixed several
things in this area.
I run GDB on target boards, over NFS root, with limited RAM, and full
debug info for libc and libstdc++. When I mess up lazy loading, I
_notice_. At least I'm not working on the 3MHz FPGA right now.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer