Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750782AbWIMND6 (ORCPT ); Wed, 13 Sep 2006 09:03:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750772AbWIMNDO (ORCPT ); Wed, 13 Sep 2006 09:03:14 -0400 Received: from mx1.redhat.com ([66.187.233.31]:42182 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1750773AbWIMNDJ (ORCPT ); Wed, 13 Sep 2006 09:03:09 -0400 From: David Howells Subject: [PATCH 5/6] Alter get_order() so that it can make use of long_log2() on a constant Date: Wed, 13 Sep 2006 14:03:02 +0100 To: torvalds@osdl.org, akpm@osdl.org Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, dhowells@redhat.com Message-Id: <20060913130302.32022.98771.stgit@warthog.cambridge.redhat.com> In-Reply-To: <20060913130253.32022.69230.stgit@warthog.cambridge.redhat.com> References: <20060913130253.32022.69230.stgit@warthog.cambridge.redhat.com> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit User-Agent: StGIT/0.10 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3676 Lines: 123 From: David Howells Alter get_order() so that it can make use of long_log2() on a constant to produce a constant value, retaining the ability for an arch to override it in the non-const case. Signed-Off-By: David Howells --- include/asm-generic/page.h | 14 ------------- include/linux/log2.h | 46 ++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 44 insertions(+), 16 deletions(-) diff --git a/include/asm-generic/page.h b/include/asm-generic/page.h index a96b5d9..a7e374e 100644 --- a/include/asm-generic/page.h +++ b/include/asm-generic/page.h @@ -6,20 +6,6 @@ #ifndef __ASSEMBLY__ #include -/* Pure 2^n version of get_order */ -static __inline__ __attribute_const__ int get_order(unsigned long size) -{ - int order; - - size = (size - 1) >> (PAGE_SHIFT - 1); - order = -1; - do { - size >>= 1; - order++; - } while (size); - return order; -} - #endif /* __ASSEMBLY__ */ #endif /* __KERNEL__ */ diff --git a/include/linux/log2.h b/include/linux/log2.h index 9bef055..a2f6858 100644 --- a/include/linux/log2.h +++ b/include/linux/log2.h @@ -1,4 +1,4 @@ -/* Log base 2 calculation +/* Base 2 logarithm calculation stuff * * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) @@ -25,6 +25,7 @@ int ____log2_NaN(void); * non-constant log of base 2 calculation * - the arch may override these in asm/bitops.h if they can be implemented * more efficiently than using fls() and fls64() + * - the arch is not required to handle n==0 if implementing the fallback */ #ifndef ARCH_HAS_LOG2 static inline __attribute__((const)) @@ -43,6 +44,36 @@ int __ll_log2(u64 n) #endif /* + * non-const pure 2^n version of get_order + * - the arch may override these in asm/bitops.h if they can be implemented + * more efficiently than using the arch log2 routines + * - we use the non-const log2() instead if the arch has defined one suitable + */ +#ifndef ARCH_HAS_GET_ORDER +static inline __attribute__((const)) +int __get_order(unsigned long size, int page_shift) +{ +#if BITS_PER_LONG == 32 && defined(ARCH_HAS_LOG2) + int order = __log2(size) - page_shift; + return order >= 0 ? order : 0; +#elif BITS_PER_LONG == 64 && defined(ARCH_HAS_LL_LOG2) + int order = __ll_log2(size) - page_shift; + return order >= 0 ? order : 0; +#else + int order; + + size = (size - 1) >> (page_shift - 1); + order = -1; + do { + size >>= 1; + order++; + } while (size); + return order; +#endif +} +#endif + +/* * constant-capable 32-bit log of base 2 calculation * - this can be used to initialise global variables from constant data, hence * the massive ternary operator construction @@ -167,7 +198,7 @@ ( \ ) /* - * constant-capable unsigned long log of base 2 calculation + * constant-capable log of base 2 calculation of unsigned long * - this can be used to initialise global variables from constant data */ #if BITS_PER_LONG == 32 @@ -176,4 +207,15 @@ #else #define long_log2(n) ll_log2(n) #endif +/* + * calculate allocation order based on the current page size + * - this can be used to initialise global variables from constant data + */ +#define get_order(n) \ +( \ + __builtin_constant_p(n) ? \ + ((n < (1UL << PAGE_SHIFT)) ? 0 : long_log2(n) - PAGE_SHIFT) : \ + __get_order(n, PAGE_SHIFT) \ + ) + #endif /* _LINUX_LOG2_H */ - 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/