The intent of this patch is to speed up the symbols resolution process. This objective is achieved by sorting all ksymtab* and kcrctab* symbols (those which reside both in the kernel and in the modules) and thus use the fast binary search. To avoid adding lots of code for symbols sorting I rely on the linker which can easily do the job thanks to a little trick. The trick isn't really beautiful to see but permits minimal changes to the code and build process. Indeed the patch is very simple and short. In the first place I changed the code for place every symbol in a different section (for example: "___ksymtab" sec "__" #sym) at compile time (this the above mentioned trick!). Thus I request to the linker to sort and merge all these sections into the appropriate ones (for example: "__ksymtab") at link time using the linker scripts. Once all symbols are sorted we can use binary search instead of the linear one. I'm fairly sure that this is a good speed improvement even though I haven't made any comprehensive benchmarking (but follow a simple one). In any case I would be very happy to receive suggestions about how made it. Collaterally, the boot time should be reduced also (proportionally to the number of modules and symbols nvolved at boot stage). I hope that you find that interesting! This work was supported by a hardware donation from the CE Linux Forum. Thanks to Ian Lance Taylor for help about how the linker works. Changes since V2: *) Fix a bug in each_symbol() semantics by Anders Kaseorg *) Split the work in three patches as requested by Rusty Russell *) Add a generic binary search implementation made by Tim Abbott *) Remove CONFIG_SYMBOLS_BSEARCH kernel option Changes since V1: *) Merge all patches into only one *) Remove few useless things *) Introduce CONFIG_SYMBOLS_BSEARCH kernel option Alessio Igor Bogani (3): module: Split the find_symbol_in_section function module: Sort exported symbols module: Use the binary search for symbols resolution Tim Abbott (1): lib: Add generic binary search function to the kernel. include/asm-generic/vmlinux.lds.h | 20 +++++++------- include/linux/bsearch.h | 9 ++++++ include/linux/module.h | 7 +++-- kernel/module.c | 37 ++++++++++++++++--------- lib/Makefile | 3 +- lib/bsearch.c | 53 +++++++++++++++++++++++++++++++++++++ scripts/module-common.lds | 11 +++++++ 7 files changed, 113 insertions(+), 27 deletions(-) create mode 100644 include/linux/bsearch.h create mode 100644 lib/bsearch.c -- To unsubscribe from this list: send the line "unsubscribe linux-embedded" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
