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mm/numa: Allow override of kernel's default NUMA policy

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Add numa_policy kernel argument to allow overriding the kernel's default
NUMA policy at boot time.

Syntax identical to what tmpfs accepts as it's mpol argument is accepted.

Some examples:

 numa_policy=interleave
 numa_policy=interleave=skip-interleave
 numa_policy=bind:0-3,5,7,9-15
 numa_policy=bind=static:1-2

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
This commit is contained in:
Tvrtko Ursulin
2024-05-22 17:12:16 +01:00
committed by Dom Cobley
parent 1c12ca6cae
commit c920cac40a
1 changed files with 42 additions and 7 deletions
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49
mm/mempolicy.c
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@@ -3310,7 +3310,9 @@ void __init numa_policy_init(void)
/* Reset policy of current process to default */
void numa_default_policy(void)
{
do_set_mempolicy(MPOL_DEFAULT, 0, NULL);
struct mempolicy *pol = &default_policy;
do_set_mempolicy(pol->mode, pol->flags, &pol->nodes);
}
/*
@@ -3327,7 +3329,6 @@ static const char * const policy_modes[] =
[MPOL_PREFERRED_MANY] = "prefer (many)",
};
#ifdef CONFIG_TMPFS
/**
* mpol_parse_str - parse string to mempolicy, for tmpfs mpol mount option.
* @str: string containing mempolicy to parse
@@ -3340,13 +3341,18 @@ static const char * const policy_modes[] =
*/
int mpol_parse_str(char *str, struct mempolicy **mpol)
{
struct mempolicy *new = NULL;
struct mempolicy *new;
unsigned short mode_flags;
nodemask_t nodes;
char *nodelist = strchr(str, ':');
char *flags = strchr(str, '=');
int err = 1, mode;
if (*mpol)
new = *mpol;
else
new = NULL;
if (flags)
*flags++ = '\0'; /* terminate mode string */
@@ -3426,9 +3432,16 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
goto out;
}
new = mpol_new(mode, mode_flags, &nodes);
if (IS_ERR(new))
goto out;
if (!new) {
new = mpol_new(mode, mode_flags, &nodes);
if (IS_ERR(new))
goto out;
} else {
atomic_set(&new->refcnt, 1);
new->mode = mode;
new->flags = mode_flags;
new->home_node = NUMA_NO_NODE;
}
/*
* Save nodes for mpol_to_str() to show the tmpfs mount options
@@ -3461,7 +3474,29 @@ out:
*mpol = new;
return err;
}
#endif /* CONFIG_TMPFS */
static int __init setup_numapolicy(char *str)
{
struct mempolicy pol = { }, *ppol = &pol;
char buf[128];
int ret;
if (str)
ret = mpol_parse_str(str, &ppol);
else
ret = -EINVAL;
if (!ret) {
default_policy = pol;
mpol_to_str(buf, sizeof(buf), &pol);
pr_info("NUMA default policy overridden to '%s'\n", buf);
} else {
pr_warn("Unable to parse numa_policy=\n");
}
return ret == 0;
}
__setup("numa_policy=", setup_numapolicy);
/**
* mpol_to_str - format a mempolicy structure for printing