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Date: Mon, 26 Feb 2007 17:35:17 -0800
From: Stephen Hemminger <shemminger@...ux-foundation.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] udivdi3: 64 bit divide
The kernel already has several implmentations and usages of 64 by 64
bit divide.
Although it is significantly slower, there are places that need it so
provide one generic version using scaling, and allow existing platform
versions to continue.
This looks like good -mm material. Tested on x86_64 and i386.
Signed-off-by: Stephen Hemminger <shemminger@...ux-foundation.org>
---
arch/alpha/Kconfig | 4 ++++
arch/arm/Kconfig | 4 ++++
arch/arm26/Kconfig | 4 ++++
arch/avr32/Kconfig | 4 ++++
arch/cris/Kconfig | 4 ++++
arch/frv/Kconfig | 4 ++++
arch/h8300/Kconfig | 4 ++++
arch/i386/Kconfig | 4 ++++
arch/m32r/Kconfig | 4 ++++
arch/m68k/Kconfig | 4 ++++
arch/m68knommu/Kconfig | 4 ++++
arch/mips/Kconfig | 4 ++++
arch/parisc/Kconfig | 4 ++++
arch/powerpc/Kconfig | 4 ++++
arch/ppc/Kconfig | 4 ++++
arch/s390/Kconfig | 4 ++++
arch/sh64/Kconfig | 4 ++++
arch/v850/Kconfig | 3 +++
arch/xtensa/Kconfig | 4 ++++
lib/Makefile | 1 +
lib/udivdi3.c | 37 +++++++++++++++++++++++++++++++++++++
net/ipv4/tcp_cubic.c | 24 +-----------------------
net/netfilter/xt_connbytes.c | 19 +------------------
23 files changed, 115 insertions(+), 41 deletions(-)
--- pktgen.orig/net/ipv4/tcp_cubic.c 2007-02-26 13:40:08.000000000 -0800
+++ pktgen/net/ipv4/tcp_cubic.c 2007-02-26 14:31:41.000000000 -0800
@@ -51,7 +51,6 @@
module_param(tcp_friendliness, int, 0644);
MODULE_PARM_DESC(tcp_friendliness, "turn on/off tcp friendliness");
-#include <asm/div64.h>
/* BIC TCP Parameters */
struct bictcp {
@@ -93,27 +92,6 @@
tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
}
-/* 64bit divisor, dividend and result. dynamic precision */
-static inline u_int64_t div64_64(u_int64_t dividend, u_int64_t divisor)
-{
- u_int32_t d = divisor;
-
- if (divisor > 0xffffffffULL) {
- unsigned int shift = fls(divisor >> 32);
-
- d = divisor >> shift;
- dividend >>= shift;
- }
-
- /* avoid 64 bit division if possible */
- if (dividend >> 32)
- do_div(dividend, d);
- else
- dividend = (uint32_t) dividend / d;
-
- return dividend;
-}
-
/*
* calculate the cubic root of x using Newton-Raphson
*/
@@ -134,7 +112,7 @@
*/
do {
x1 = x;
- x = (2 * x + (uint32_t) div64_64(a, x*x)) / 3;
+ x = (2 * x + (u32) (a / (x*x))) / 3;
} while (abs(x1 - x) > 1);
return x;
--- pktgen.orig/net/netfilter/xt_connbytes.c 2007-02-26 13:40:08.000000000 -0800
+++ pktgen/net/netfilter/xt_connbytes.c 2007-02-26 14:29:13.000000000 -0800
@@ -16,7 +16,6 @@
#include <linux/netfilter/x_tables.h>
#include <linux/netfilter/xt_connbytes.h>
-#include <asm/div64.h>
#include <asm/bitops.h>
MODULE_LICENSE("GPL");
@@ -24,22 +23,6 @@
MODULE_DESCRIPTION("iptables match for matching number of pkts/bytes per connection");
MODULE_ALIAS("ipt_connbytes");
-/* 64bit divisor, dividend and result. dynamic precision */
-static u_int64_t div64_64(u_int64_t dividend, u_int64_t divisor)
-{
- u_int32_t d = divisor;
-
- if (divisor > 0xffffffffULL) {
- unsigned int shift = fls(divisor >> 32);
-
- d = divisor >> shift;
- dividend >>= shift;
- }
-
- do_div(dividend, d);
- return dividend;
-}
-
static int
match(const struct sk_buff *skb,
const struct net_device *in,
@@ -106,7 +89,7 @@
break;
}
if (pkts != 0)
- what = div64_64(bytes, pkts);
+ what = bytes / pkts;
break;
}
--- pktgen.orig/lib/Makefile 2007-02-26 13:40:08.000000000 -0800
+++ pktgen/lib/Makefile 2007-02-26 14:17:31.000000000 -0800
@@ -28,6 +28,7 @@
lib-$(CONFIG_SEMAPHORE_SLEEPERS) += semaphore-sleepers.o
lib-$(CONFIG_GENERIC_FIND_NEXT_BIT) += find_next_bit.o
obj-$(CONFIG_GENERIC_HWEIGHT) += hweight.o
+obj-$(CONFIG_GENERIC_UDIVDI3) += udivdi3.o
obj-$(CONFIG_LOCK_KERNEL) += kernel_lock.o
obj-$(CONFIG_PLIST) += plist.o
obj-$(CONFIG_DEBUG_PREEMPT) += smp_processor_id.o
--- pktgen.orig/arch/alpha/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/alpha/Kconfig 2007-02-26 13:54:35.000000000 -0800
@@ -33,6 +33,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/arm/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/arm/Kconfig 2007-02-26 13:54:57.000000000 -0800
@@ -90,6 +90,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_HWEIGHT
bool
default y
--- pktgen.orig/arch/arm26/Kconfig 2007-02-26 13:48:46.000000000 -0800
+++ pktgen/arch/arm26/Kconfig 2007-02-26 13:55:24.000000000 -0800
@@ -49,6 +49,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_HWEIGHT
bool
default y
--- pktgen.orig/arch/avr32/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/avr32/Kconfig 2007-02-26 13:55:39.000000000 -0800
@@ -53,6 +53,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_BUST_SPINLOCK
bool
--- pktgen.orig/arch/cris/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/cris/Kconfig 2007-02-26 13:55:53.000000000 -0800
@@ -28,6 +28,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/frv/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/frv/Kconfig 2007-02-26 13:56:09.000000000 -0800
@@ -53,6 +53,10 @@
bool
default y
+config GENERIC_UDIVDI3
+ bool
+ default y
+
mainmenu "Fujitsu FR-V Kernel Configuration"
source "init/Kconfig"
--- pktgen.orig/arch/h8300/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/h8300/Kconfig 2007-02-26 13:56:20.000000000 -0800
@@ -41,6 +41,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/i386/Kconfig 2007-02-26 14:01:59.000000000 -0800
+++ pktgen/arch/i386/Kconfig 2007-02-26 14:02:28.000000000 -0800
@@ -75,6 +75,10 @@
bool
default y
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config ARCH_MAY_HAVE_PC_FDC
bool
default y
--- pktgen.orig/arch/m32r/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/m32r/Kconfig 2007-02-26 13:56:43.000000000 -0800
@@ -229,6 +229,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/m68k/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/m68k/Kconfig 2007-02-26 13:56:56.000000000 -0800
@@ -25,6 +25,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_HWEIGHT
bool
default y
--- pktgen.orig/arch/m68knommu/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/m68knommu/Kconfig 2007-02-26 13:57:05.000000000 -0800
@@ -37,6 +37,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/mips/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/mips/Kconfig 2007-02-26 13:57:13.000000000 -0800
@@ -843,6 +843,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/parisc/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/parisc/Kconfig 2007-02-26 13:57:21.000000000 -0800
@@ -33,6 +33,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/powerpc/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/powerpc/Kconfig 2007-02-26 13:57:31.000000000 -0800
@@ -49,6 +49,10 @@
bool
default y if 64BIT
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_HWEIGHT
bool
default y
--- pktgen.orig/arch/ppc/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/ppc/Kconfig 2007-02-26 13:57:44.000000000 -0800
@@ -27,6 +27,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_HWEIGHT
bool
default y
--- pktgen.orig/arch/s390/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/s390/Kconfig 2007-02-26 13:57:53.000000000 -0800
@@ -34,6 +34,10 @@
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_HWEIGHT
bool
default y
--- pktgen.orig/arch/sh64/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/sh64/Kconfig 2007-02-26 14:00:32.000000000 -0800
@@ -21,6 +21,10 @@
bool
default y
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/v850/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/v850/Kconfig 2007-02-26 13:59:29.000000000 -0800
@@ -19,6 +19,9 @@
config RWSEM_XCHGADD_ALGORITHM
bool
default n
+config GENERIC_UDIVDI3
+ bool
+ default y
config GENERIC_FIND_NEXT_BIT
bool
default y
--- pktgen.orig/arch/xtensa/Kconfig 2007-02-26 13:51:29.000000000 -0800
+++ pktgen/arch/xtensa/Kconfig 2007-02-26 13:59:45.000000000 -0800
@@ -26,6 +26,10 @@
bool
default y
+config GENERIC_UDIVDI3
+ bool
+ default y
+
config GENERIC_FIND_NEXT_BIT
bool
default y
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ pktgen/lib/udivdi3.c 2007-02-26 14:14:13.000000000 -0800
@@ -0,0 +1,37 @@
+/*
+ * Generic C version of full 64 bit by 64 bit division
+ * Extracted from version used by netfilter connection tracking
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * Code generated for this function might be very inefficient
+ * for some CPUs, can be overridden by linking arch-specific
+ * assembly versions such as arch/sparc/lib/udivdi.S
+ */
+#include <linux/types.h>
+#include <linux/module.h>
+#include <asm/div64.h>
+
+uint64_t __udivdi3(uint64_t dividend, uint64_t divisor)
+{
+ uint32_t d = divisor;
+
+ /* Scale divisor to 32 bits */
+ if (divisor > 0xffffffffULL) {
+ unsigned int shift = fls(divisor >> 32);
+
+ d = divisor >> shift;
+ dividend >>= shift;
+ }
+
+ /* avoid 64 bit division if possible */
+ if (dividend >> 32)
+ do_div(dividend, d);
+ else
+ dividend = (uint32_t) dividend / d;
+
+ return dividend;
+}
+EXPORT_SYMBOL(__udivdi3);
-
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