Re: [Qemu-devel] [PATCH] Improve symbol lookup (was: Re: [Qemu-devel] [PATCH] Fix symbol lookup for mips64* targets)

[Laurent Desnogues]

On Thu, Oct 16, 2008 at 9:57 PM, Stefan Weil <address@hidden> wrote:
>
> So I did. Here is a short summary of my new patch:
>
> * Use function pointers for symbol lookup (currently for elf32 and
> elf64, could be expanded).
>  This also fixes the bug with mips elf64 symbols in current Qemu trunk.
>
> * Use quicksort and binary search for symbol lookup.
>
> * Remove unneeded entries from symbol table.
>  This reduced a typical table size (linux mips kernel) from 1764487 to
> 11656 entries.
>
> * In disas.c, the patch also fixes some warnings from old fashioned
> function prototypes.
>
> In loader.c, two defines control some compile time options (could be
> removed in
> production code):
> #define CONFIG_BINARY_SYMBOL_SEARCH
> #define CONFIG_REDUCE_SYMBOL_TABLE
>
> I tested the new code using 32 bit and 64 bit linux mips kernels and
> Qemu logging (-d in_asm).
> The speed improvement is extremely large - both because of the much
> smaller table and
> the binary search.

Nice!  Did you profile the time spent looking up symbols
when running some big executable with a big symbol table?


Laurent