Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754271Ab1DPN0b (ORCPT ); Sat, 16 Apr 2011 09:26:31 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:49434 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751106Ab1DPN0X (ORCPT ); Sat, 16 Apr 2011 09:26:23 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:from:to:cc:subject:date:message-id:x-mailer:mime-version :content-type:content-transfer-encoding; b=rDcSHQ7i40zwZOlxyztaqZb9e2wb1da6VKLZsl63ZpnRZAFHY1ZJalNpEf6LFnDvJa rNvxCK/GbC33v2Mx5bJAtEpKTA20JU5HYhM4QmWVJXlUObiIyoPF74z5nY61Np9zLUHj x8sX9IAk3Ydmsaey7VG5G+WFUitIZbzNYZT3A= From: Alessio Igor Bogani To: Rusty Russell , Tim Abbott , Anders Kaseorg , Jason Wessel , Tim Bird Cc: LKML , Linux Embedded , Alessio Igor Bogani Subject: [PATCH 0/4] Speed up the symbols' resolution process V4 Date: Sat, 16 Apr 2011 15:26:09 +0200 Message-Id: <1302960373-5309-1-git-send-email-abogani@kernel.org> X-Mailer: git-send-email 1.7.4.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2896 Lines: 73 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 V3: *) Please ignore this version completely 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: Restructure each_symbol() code 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 | 4 +- kernel/module.c | 84 ++++++++++++++++++++++++++++--------- lib/Makefile | 3 +- lib/bsearch.c | 53 +++++++++++++++++++++++ scripts/module-common.lds | 11 +++++ 7 files changed, 151 insertions(+), 33 deletions(-) create mode 100644 include/linux/bsearch.h create mode 100644 lib/bsearch.c -- 1.7.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/