From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id AD1FB900194 for ; Wed, 22 Jun 2011 15:46:17 -0400 (EDT) Received: from wpaz17.hot.corp.google.com (wpaz17.hot.corp.google.com [172.24.198.81]) by smtp-out.google.com with ESMTP id p5MJkD8u006661 for ; Wed, 22 Jun 2011 12:46:13 -0700 Received: from pzk37 (pzk37.prod.google.com [10.243.19.165]) by wpaz17.hot.corp.google.com with ESMTP id p5MJk7we002335 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Wed, 22 Jun 2011 12:46:11 -0700 Received: by pzk37 with SMTP id 37so827756pzk.29 for ; Wed, 22 Jun 2011 12:46:07 -0700 (PDT) Message-ID: <4E02467C.6090106@google.com> Date: Wed, 22 Jun 2011 12:46:04 -0700 From: Mike Ditto MIME-Version: 1.0 Subject: [PATCH] x86: e820: Eliminate bubble sort from sanitize_e820_map References: <1308741534-6846-1-git-send-email-sassmann@kpanic.de> <20110622110034.89ee399c.akpm@linux-foundation.org> In-Reply-To: <20110622110034.89ee399c.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Stefan Assmann , linux-mm@kvack.org, linux-kernel@vger.kernel.org, tony.luck@intel.com, andi@firstfloor.org, mingo@elte.hu, hpa@zytor.com, rick@vanrein.org, rdunlap@xenotime.net, Nancy Yuen Replace the bubble sort in sanitize_e820_map() with a call to the generic kernel sort function to avoid pathological performance with large maps. On large (thousands of entries) E820 maps, the previous code took minutes to run; with this change it's now milliseconds. Signed-off-by: Mike Ditto --- This is a small independent part of Google's BadRAM changes mentioned in another thread. arch/x86/kernel/e820.c | 59 +++++++++++++++++++---------------------------- 1 files changed, 24 insertions(+), 35 deletions(-) diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 3e2ef84..e2e212a 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include @@ -226,22 +227,38 @@ void __init e820_print_map(char *who) * ____________________33__ * ______________________4_ */ +struct change_member { + struct e820entry *pbios; /* pointer to original bios entry */ + unsigned long long addr; /* address for this change point */ +}; + +static int __init cpcompare(const void *a, const void *b) +{ + struct change_member * const *app = a, * const *bpp = b; + const struct change_member *ap = *app, *bp = *bpp; + + /* + * Inputs are pointers to two elements of change_point[]. If their + * addresses are unequal, their difference dominates. If the addresses + * are equal, then consider one that represents the end of its region + * to be greater than one that does not. + */ + if (ap->addr != bp->addr) + return ap->addr > bp->addr ? 1 : -1; + + return (ap->addr != ap->pbios->addr) - (bp->addr != bp->pbios->addr); +} int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map, u32 *pnr_map) { - struct change_member { - struct e820entry *pbios; /* pointer to original bios entry */ - unsigned long long addr; /* address for this change point */ - }; static struct change_member change_point_list[2*E820_X_MAX] __initdata; static struct change_member *change_point[2*E820_X_MAX] __initdata; static struct e820entry *overlap_list[E820_X_MAX] __initdata; static struct e820entry new_bios[E820_X_MAX] __initdata; - struct change_member *change_tmp; unsigned long current_type, last_type; unsigned long long last_addr; - int chgidx, still_changing; + int chgidx; int overlap_entries; int new_bios_entry; int old_nr, new_nr, chg_nr; @@ -278,35 +295,7 @@ int __init sanitize_e820_map(struct e820entry *biosmap, int max_nr_map, chg_nr = chgidx; /* sort change-point list by memory addresses (low -> high) */ - still_changing = 1; - while (still_changing) { - still_changing = 0; - for (i = 1; i < chg_nr; i++) { - unsigned long long curaddr, lastaddr; - unsigned long long curpbaddr, lastpbaddr; - - curaddr = change_point[i]->addr; - lastaddr = change_point[i - 1]->addr; - curpbaddr = change_point[i]->pbios->addr; - lastpbaddr = change_point[i - 1]->pbios->addr; - - /* - * swap entries, when: - * - * curaddr > lastaddr or - * curaddr == lastaddr and curaddr == curpbaddr and - * lastaddr != lastpbaddr - */ - if (curaddr < lastaddr || - (curaddr == lastaddr && curaddr == curpbaddr && - lastaddr != lastpbaddr)) { - change_tmp = change_point[i]; - change_point[i] = change_point[i-1]; - change_point[i-1] = change_tmp; - still_changing = 1; - } - } - } + sort(change_point, chg_nr, sizeof *change_point, cpcompare, 0); /* create a new bios memory map, removing overlaps */ overlap_entries = 0; /* number of entries in the overlap table */ -- 1.7.3.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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