Revision 01599fca6758d2cd133e78f87426fc851c9ea725 authored by Andrew Morton on 13 April 2009, 17:27:49 UTC, committed by Linus Torvalds on 13 April 2009, 18:09:46 UTC
Atttempting to rid us of the problematic work_on_cpu(). Just use smp_call_fuction_single() here. This repairs a 10% sysbench(oltp)+mysql regression which Mike reported, due to commit 6b44003e5ca66a3fffeb5bc90f40ada2c4340896 Author: Andrew Morton <akpm@linux-foundation.org> Date: Thu Apr 9 09:50:37 2009 -0600 work_on_cpu(): rewrite it to create a kernel thread on demand It seems that the kernel calls these acpi-cpufreq functions at a quite high frequency. Valdis Kletnieks also reports that this causes 70-90 forks per second on his hardware. Cc: Valdis.Kletnieks@vt.edu Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> Cc: Len Brown <len.brown@intel.com> Cc: Zhao Yakui <yakui.zhao@intel.com> Acked-by: Dave Jones <davej@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Tested-by: Mike Galbraith <efault@gmx.de> Cc: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Ingo Molnar <mingo@elte.hu> [ Made it use smp_call_function_many() instead of looping over cpu's with smp_call_function_single() - Linus ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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argv_split.c
/*
* Helper function for splitting a string into an argv-like array.
*/
#include <linux/kernel.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/module.h>
static const char *skip_sep(const char *cp)
{
while (*cp && isspace(*cp))
cp++;
return cp;
}
static const char *skip_arg(const char *cp)
{
while (*cp && !isspace(*cp))
cp++;
return cp;
}
static int count_argc(const char *str)
{
int count = 0;
while (*str) {
str = skip_sep(str);
if (*str) {
count++;
str = skip_arg(str);
}
}
return count;
}
/**
* argv_free - free an argv
* @argv - the argument vector to be freed
*
* Frees an argv and the strings it points to.
*/
void argv_free(char **argv)
{
char **p;
for (p = argv; *p; p++)
kfree(*p);
kfree(argv);
}
EXPORT_SYMBOL(argv_free);
/**
* argv_split - split a string at whitespace, returning an argv
* @gfp: the GFP mask used to allocate memory
* @str: the string to be split
* @argcp: returned argument count
*
* Returns an array of pointers to strings which are split out from
* @str. This is performed by strictly splitting on white-space; no
* quote processing is performed. Multiple whitespace characters are
* considered to be a single argument separator. The returned array
* is always NULL-terminated. Returns NULL on memory allocation
* failure.
*/
char **argv_split(gfp_t gfp, const char *str, int *argcp)
{
int argc = count_argc(str);
char **argv = kzalloc(sizeof(*argv) * (argc+1), gfp);
char **argvp;
if (argv == NULL)
goto out;
if (argcp)
*argcp = argc;
argvp = argv;
while (*str) {
str = skip_sep(str);
if (*str) {
const char *p = str;
char *t;
str = skip_arg(str);
t = kstrndup(p, str-p, gfp);
if (t == NULL)
goto fail;
*argvp++ = t;
}
}
*argvp = NULL;
out:
return argv;
fail:
argv_free(argv);
return NULL;
}
EXPORT_SYMBOL(argv_split);
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