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Commit 22f2e280 authored by Derek Fults's avatar Derek Fults Committed by Linus Torvalds
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[PATCH] get_options to allow a hypenated range for isolcpus 



This allows a hyphenated range of positive numbers in the string passed
to command line helper function, get_options.

Currently the command line option "isolcpus=" takes as its argument a
list of cpus.

Format: <cpu number>,...,<cpu number>
Valid values of <cpu_number>  include all cpus, 0 to "number of CPUs in
system - 1". This can get extremely long when isolating the majority of
cpus on a large system.  The kernel isolcpus code would not need any
changing to use this feature.  To use it, the change would be in the
command line format for 'isolcpus='
Format:
<cpu number>,...,<cpu number>
or
<cpu number>-<cpu number>  (must be a positive range in ascending
order.)
or a mixture
<cpu number>,...,<cpu number>-<cpu number>

Signed-off-by: default avatarDerek Fults <dfults@sgi.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 8f63fdbb

Documentation/kernel-parameters.txt

+6 −1
Original line number Diff line number Diff line
@@ -714,7 +714,12 @@ and is between 256 and 4096 characters. It is defined in the file 
			Format: <RDP>,<reset>,<pci_scan>,<verbosity>



	isolcpus=	[KNL,SMP] Isolate CPUs from the general scheduler.

			Format: <cpu number>,...,<cpu number>

			Format:

			<cpu number>,...,<cpu number>

			or

			<cpu number>-<cpu number>  (must be a positive range in ascending order)

			or a mixture

			<cpu number>,...,<cpu number>-<cpu number>

			This option can be used to specify one or more CPUs

			to isolate from the general SMP balancing and scheduling

			algorithms. The only way to move a process onto or off

lib/cmdline.c

+34 −1
Original line number Diff line number Diff line
@@ -16,6 +16,23 @@ 
#include <linux/kernel.h>

#include <linux/string.h>



/*

 *	If a hyphen was found in get_option, this will handle the

 *	range of numbers, M-N.  This will expand the range and insert

 *	the values[M, M+1, ..., N] into the ints array in get_options.

 */



static int get_range(char **str, int *pint)

{

	int x, inc_counter, upper_range;



	(*str)++;

	upper_range = simple_strtol((*str), NULL, 0);

	inc_counter = upper_range - *pint;

	for (x = *pint; x < upper_range; x++)

		*pint++ = x;

	return inc_counter;

}



/**

 *	get_option - Parse integer from an option string
@@ -29,6 +46,7 @@ 
 *	0 : no int in string

 *	1 : int found, no subsequent comma

 *	2 : int found including a subsequent comma

 *	3 : hyphen found to denote a range

 */



int get_option (char **str, int *pint)
@@ -44,6 +62,8 @@ int get_option (char **str, int *pint) 
		(*str)++;

		return 2;

	}

	if (**str == '-')

		return 3;



	return 1;

}
@@ -55,7 +75,8 @@ int get_option (char **str, int *pint) 
 *	@ints: integer array

 *

 *	This function parses a string containing a comma-separated

 *	list of integers.  The parse halts when the array is

 *	list of integers, a hyphen-separated range of _positive_ integers,

 *	or a combination of both.  The parse halts when the array is

 *	full, or when no more numbers can be retrieved from the

 *	string.

 *
@@ -72,6 +93,18 @@ char *get_options(const char *str, int nints, int *ints) 
		res = get_option ((char **)&str, ints + i);

		if (res == 0)

			break;

		if (res == 3) {

			int range_nums;

			range_nums = get_range((char **)&str, ints + i);

			if (range_nums < 0)

				break;

			/*

			 * Decrement the result by one to leave out the

			 * last number in the range.  The next iteration

			 * will handle the upper number in the range

			 */

			i += (range_nums - 1);

		}

		i++;

		if (res == 1)

			break;