[PATCH] reduce large stack usage

[PATCH] reduce large stack usage

[Randy.Dunlap]

[-- Attachment #1: Type: text/plain, Size: 279 bytes --]

Hi,

This patch to 2.5.63 reduces stack usage in generate_default_upcase()
from 0x3d4 bytes to just noise (on x86).

The arrays are static so they are still private (hidden), but
now they aren't allocated on the stack and copied there for
temp use.

Please apply.

Thanks,
~Randy

[-- Attachment #2: ntfs_stack_2563.patch --]
[-- Type: text/plain, Size: 1843 bytes --]

patch_name:	ntfs_stack_2563.patch
patch_version:	2003-02-28.22:42:57
author:		Randy.Dunlap <rddunlap@osdl.org>
description:	ntfs: reduce function local stack usage from 0x3d4 bytes to just noise;
product:	Linux
product_versions: linux-2563
changelog:	_
URL:		_
requires:	_
conflicts:	_
maintainer:	Anton Altaparmakov <aia21@cantab.net>
diffstat:	=
 fs/ntfs/upcase.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff -Naur ./fs/ntfs/upcase.c%NTSTK ./fs/ntfs/upcase.c
--- ./fs/ntfs/upcase.c%NTSTK	Mon Feb 24 11:05:05 2003
+++ ./fs/ntfs/upcase.c	Fri Feb 28 22:37:32 2003
@@ -26,9 +26,7 @@
 
 #include "ntfs.h"
 
-uchar_t *generate_default_upcase(void)
-{
-	const int uc_run_table[][3] = { /* Start, End, Add */
+static const int uc_run_table[][3] = { /* Start, End, Add */
 	{0x0061, 0x007B,  -32}, {0x0451, 0x045D, -80}, {0x1F70, 0x1F72,  74},
 	{0x00E0, 0x00F7,  -32}, {0x045E, 0x0460, -80}, {0x1F72, 0x1F76,  86},
 	{0x00F8, 0x00FF,  -32}, {0x0561, 0x0587, -48}, {0x1F76, 0x1F78, 100},
@@ -45,7 +43,7 @@
 	{0}
 	};
 
-	const int uc_dup_table[][2] = { /* Start, End */
+static const int uc_dup_table[][2] = { /* Start, End */
 	{0x0100, 0x012F}, {0x01A0, 0x01A6}, {0x03E2, 0x03EF}, {0x04CB, 0x04CC},
 	{0x0132, 0x0137}, {0x01B3, 0x01B7}, {0x0460, 0x0481}, {0x04D0, 0x04EB},
 	{0x0139, 0x0149}, {0x01CD, 0x01DD}, {0x0490, 0x04BF}, {0x04EE, 0x04F5},
@@ -55,7 +53,7 @@
 	{0}
 	};
 
-	const int uc_word_table[][2] = { /* Offset, Value */
+static const int uc_word_table[][2] = { /* Offset, Value */
 	{0x00FF, 0x0178}, {0x01AD, 0x01AC}, {0x01F3, 0x01F1}, {0x0269, 0x0196},
 	{0x0183, 0x0182}, {0x01B0, 0x01AF}, {0x0253, 0x0181}, {0x026F, 0x019C},
 	{0x0185, 0x0184}, {0x01B9, 0x01B8}, {0x0254, 0x0186}, {0x0272, 0x019D},
@@ -67,6 +65,8 @@
 	{0}
 	};
 
+uchar_t *generate_default_upcase(void)
+{
 	int i, r;
 	uchar_t *uc;
 

Re: [Linux-NTFS-Dev] [PATCH] reduce large stack usage

[Andrew Clausen]

Hi Randy,

On Fri, Feb 28, 2003 at 11:06:23PM -0800, Randy.Dunlap wrote:
> This patch to 2.5.63 reduces stack usage in generate_default_upcase()
> from 0x3d4 bytes to just noise (on x86).
> 
> The arrays are static so they are still private (hidden), but
> now they aren't allocated on the stack and copied there for
> temp use.

BTW, you can declare "local" variables inside a function as static,
which makes them "global", but locally scoped.  The code should be
basically equivalent, but perhaps more elegant...

i.e.:

 uchar_t *generate_default_upcase(void)
 {
-	const int uc_run_table[][3] = { /* Start, End, Add */
+static const int uc_run_table[][3] = { /* Start, End, Add */
 	{0x0061, 0x007B,  -32}, {0x0451, 0x045D, -80}, {0x1F70, 0x1F72,  74},
 	{0x00E0, 0x00F7,  -32}, {0x045E, 0x0460, -80}, {0x1F72, 0x1F76,  86},
 	{0x00F8, 0x00FF,  -32}, {0x0561, 0x0587, -48}, {0x1F76, 0x1F78, 100},

Cheers,
Andrew

Re: [Linux-NTFS-Dev] [PATCH] reduce large stack usage

[Randy.Dunlap]

> Hi Randy,
>
> On Fri, Feb 28, 2003 at 11:06:23PM -0800, Randy.Dunlap wrote:
>> This patch to 2.5.63 reduces stack usage in generate_default_upcase() from
>> 0x3d4 bytes to just noise (on x86).
>>
>> The arrays are static so they are still private (hidden), but
>> now they aren't allocated on the stack and copied there for
>> temp use.
>
> BTW, you can declare "local" variables inside a function as static, which
> makes them "global", but locally scoped.  The code should be basically
> equivalent, but perhaps more elegant...
>
> i.e.:
>
>  uchar_t *generate_default_upcase(void)
>  {
> -	const int uc_run_table[][3] = { /* Start, End, Add */
> +static const int uc_run_table[][3] = { /* Start, End, Add */
>  	{0x0061, 0x007B,  -32}, {0x0451, 0x045D, -80}, {0x1F70, 0x1F72,  74},
> {0x00E0, 0x00F7,  -32}, {0x045E, 0x0460, -80}, {0x1F72, 0x1F76,  86},
> {0x00F8, 0x00FF,  -32}, {0x0561, 0x0587, -48}, {0x1F76, 0x1F78, 100},
>
> Cheers,
> Andrew

Yes, of course.  I'll remake the patch unless someone else does.
(-ESLEEPY last night)

Thanks,
~Randy