[PATCH v8 06/10] selftests/mm: Factor out thp settings management

Ryan Roberts
2023-12-04T10:21:53Z

The khugepaged test has a useful framework for save/restore/pop/push of
all thp settings via the sysfs interface. This will be useful to
explicitly control multi-size THP settings in other tests, so let's
move it out of khugepaged and into its own thp_settings.[c|h] utility.

Tested-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
tools/testing/selftests/mm/Makefile | 4 +-
tools/testing/selftests/mm/khugepaged.c | 346 ++--------------------
tools/testing/selftests/mm/thp_settings.c | 296 ++++++++++++++++++
tools/testing/selftests/mm/thp_settings.h | 71 +++++
4 files changed, 391 insertions(+), 326 deletions(-)
create mode 100644 tools/testing/selftests/mm/thp_settings.c
create mode 100644 tools/testing/selftests/mm/thp_settings.h

diff --git a/tools/testing/selftests/mm/Makefile b/tools/testing/selftests/mm/Makefile
index dede0bcf97a3..2453add65d12 100644
--- a/tools/testing/selftests/mm/Makefile
+++ b/tools/testing/selftests/mm/Makefile
@@ -117,8 +117,8 @@ TEST_FILES += va_high_addr_switch.sh

include ../lib.mk

-$(TEST_GEN_PROGS): vm_util.c
-$(TEST_GEN_FILES): vm_util.c
+$(TEST_GEN_PROGS): vm_util.c thp_settings.c
+$(TEST_GEN_FILES): vm_util.c thp_settings.c

$(OUTPUT)/uffd-stress: uffd-common.c
$(OUTPUT)/uffd-unit-tests: uffd-common.c
diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index fc47a1c4944c..b15e7fd70176 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -22,13 +22,13 @@
#include "linux/magic.h"

#include "vm_util.h"
+#include "thp_settings.h"

#define BASE_ADDR ((void *)(1UL << 30))
static unsigned long hpage_pmd_size;
static unsigned long page_size;
static int hpage_pmd_nr;

-#define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
#define PID_SMAPS "/proc/self/smaps"
#define TEST_FILE "collapse_test_file"

@@ -71,78 +71,7 @@ struct file_info {
};

static struct file_info finfo;
-
-enum thp_enabled {
- THP_ALWAYS,
- THP_MADVISE,
- THP_NEVER,
-};
-
-static const char *thp_enabled_strings[] = {
- "always",
- "madvise",
- "never",
- NULL
-};
-
-enum thp_defrag {
- THP_DEFRAG_ALWAYS,
- THP_DEFRAG_DEFER,
- THP_DEFRAG_DEFER_MADVISE,
- THP_DEFRAG_MADVISE,
- THP_DEFRAG_NEVER,
-};
-
-static const char *thp_defrag_strings[] = {
- "always",
- "defer",
- "defer+madvise",
- "madvise",
- "never",
- NULL
-};
-
-enum shmem_enabled {
- SHMEM_ALWAYS,
- SHMEM_WITHIN_SIZE,
- SHMEM_ADVISE,
- SHMEM_NEVER,
- SHMEM_DENY,
- SHMEM_FORCE,
-};
-
-static const char *shmem_enabled_strings[] = {
- "always",
- "within_size",
- "advise",
- "never",
- "deny",
- "force",
- NULL
-};
-
-struct khugepaged_settings {
- bool defrag;
- unsigned int alloc_sleep_millisecs;
- unsigned int scan_sleep_millisecs;
- unsigned int max_ptes_none;
- unsigned int max_ptes_swap;
- unsigned int max_ptes_shared;
- unsigned long pages_to_scan;
-};
-
-struct settings {
- enum thp_enabled thp_enabled;
- enum thp_defrag thp_defrag;
- enum shmem_enabled shmem_enabled;
- bool use_zero_page;
- struct khugepaged_settings khugepaged;
- unsigned long read_ahead_kb;
-};
-
-static struct settings saved_settings;
static bool skip_settings_restore;
-
static int exit_status;

static void success(const char *msg)
@@ -161,226 +90,13 @@ static void skip(const char *msg)
printf(" \e[33m%s\e[0m\n", msg);
}

-static int read_file(const char *path, char *buf, size_t buflen)
-{
- int fd;
- ssize_t numread;
-
- fd = open(path, O_RDONLY);
- if (fd == -1)
- return 0;
-
- numread = read(fd, buf, buflen - 1);
- if (numread < 1) {
- close(fd);
- return 0;
- }
-
- buf[numread] = '\0';
- close(fd);
-
- return (unsigned int) numread;
-}
-
-static int write_file(const char *path, const char *buf, size_t buflen)
-{
- int fd;
- ssize_t numwritten;
-
- fd = open(path, O_WRONLY);
- if (fd == -1) {
- printf("open(%s)\n", path);
- exit(EXIT_FAILURE);
- return 0;
- }
-
- numwritten = write(fd, buf, buflen - 1);
- close(fd);
- if (numwritten < 1) {
- printf("write(%s)\n", buf);
- exit(EXIT_FAILURE);
- return 0;
- }
-
- return (unsigned int) numwritten;
-}
-
-static int read_string(const char *name, const char *strings[])
-{
- char path[PATH_MAX];
- char buf[256];
- char *c;
- int ret;
-
- ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
- if (ret >= PATH_MAX) {
- printf("%s: Pathname is too long\n", __func__);
- exit(EXIT_FAILURE);
- }
-
- if (!read_file(path, buf, sizeof(buf))) {
- perror(path);
- exit(EXIT_FAILURE);
- }
-
- c = strchr(buf, '[');
- if (!c) {
- printf("%s: Parse failure\n", __func__);
- exit(EXIT_FAILURE);
- }
-
- c++;
- memmove(buf, c, sizeof(buf) - (c - buf));
-
- c = strchr(buf, ']');
- if (!c) {
- printf("%s: Parse failure\n", __func__);
- exit(EXIT_FAILURE);
- }
- *c = '\0';
-
- ret = 0;
- while (strings[ret]) {
- if (!strcmp(strings[ret], buf))
- return ret;
- ret++;
- }
-
- printf("Failed to parse %s\n", name);
- exit(EXIT_FAILURE);
-}
-
-static void write_string(const char *name, const char *val)
-{
- char path[PATH_MAX];
- int ret;
-
- ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
- if (ret >= PATH_MAX) {
- printf("%s: Pathname is too long\n", __func__);
- exit(EXIT_FAILURE);
- }
-
- if (!write_file(path, val, strlen(val) + 1)) {
- perror(path);
- exit(EXIT_FAILURE);
- }
-}
-
-static const unsigned long _read_num(const char *path)
-{
- char buf[21];
-
- if (read_file(path, buf, sizeof(buf)) < 0) {
- perror("read_file(read_num)");
- exit(EXIT_FAILURE);
- }
-
- return strtoul(buf, NULL, 10);
-}
-
-static const unsigned long read_num(const char *name)
-{
- char path[PATH_MAX];
- int ret;
-
- ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
- if (ret >= PATH_MAX) {
- printf("%s: Pathname is too long\n", __func__);
- exit(EXIT_FAILURE);
- }
- return _read_num(path);
-}
-
-static void _write_num(const char *path, unsigned long num)
-{
- char buf[21];
-
- sprintf(buf, "%ld", num);
- if (!write_file(path, buf, strlen(buf) + 1)) {
- perror(path);
- exit(EXIT_FAILURE);
- }
-}
-
-static void write_num(const char *name, unsigned long num)
-{
- char path[PATH_MAX];
- int ret;
-
- ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
- if (ret >= PATH_MAX) {
- printf("%s: Pathname is too long\n", __func__);
- exit(EXIT_FAILURE);
- }
- _write_num(path, num);
-}
-
-static void write_settings(struct settings *settings)
-{
- struct khugepaged_settings *khugepaged = &settings->khugepaged;
-
- write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
- write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
- write_string("shmem_enabled",
- shmem_enabled_strings[settings->shmem_enabled]);
- write_num("use_zero_page", settings->use_zero_page);
-
- write_num("khugepaged/defrag", khugepaged->defrag);
- write_num("khugepaged/alloc_sleep_millisecs",
- khugepaged->alloc_sleep_millisecs);
- write_num("khugepaged/scan_sleep_millisecs",
- khugepaged->scan_sleep_millisecs);
- write_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none);
- write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap);
- write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared);
- write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan);
-
- if (file_ops && finfo.type == VMA_FILE)
- _write_num(finfo.dev_queue_read_ahead_path,
- settings->read_ahead_kb);
-}
-
-#define MAX_SETTINGS_DEPTH 4
-static struct settings settings_stack[MAX_SETTINGS_DEPTH];
-static int settings_index;
-
-static struct settings *current_settings(void)
-{
- if (!settings_index) {
- printf("Fail: No settings set");
- exit(EXIT_FAILURE);
- }
- return settings_stack + settings_index - 1;
-}
-
-static void push_settings(struct settings *settings)
-{
- if (settings_index >= MAX_SETTINGS_DEPTH) {
- printf("Fail: Settings stack exceeded");
- exit(EXIT_FAILURE);
- }
- settings_stack[settings_index++] = *settings;
- write_settings(current_settings());
-}
-
-static void pop_settings(void)
-{
- if (settings_index <= 0) {
- printf("Fail: Settings stack empty");
- exit(EXIT_FAILURE);
- }
- --settings_index;
- write_settings(current_settings());
-}
-
static void restore_settings_atexit(void)
{
if (skip_settings_restore)
return;

printf("Restore THP and khugepaged settings...");
- write_settings(&saved_settings);
+ thp_restore_settings();
success("OK");

skip_settings_restore = true;
@@ -395,27 +111,9 @@ static void restore_settings(int sig)
static void save_settings(void)
{
printf("Save THP and khugepaged settings...");
- saved_settings = (struct settings) {
- .thp_enabled = read_string("enabled", thp_enabled_strings),
- .thp_defrag = read_string("defrag", thp_defrag_strings),
- .shmem_enabled =
- read_string("shmem_enabled", shmem_enabled_strings),
- .use_zero_page = read_num("use_zero_page"),
- };
- saved_settings.khugepaged = (struct khugepaged_settings) {
- .defrag = read_num("khugepaged/defrag"),
- .alloc_sleep_millisecs =
- read_num("khugepaged/alloc_sleep_millisecs"),
- .scan_sleep_millisecs =
- read_num("khugepaged/scan_sleep_millisecs"),
- .max_ptes_none = read_num("khugepaged/max_ptes_none"),
- .max_ptes_swap = read_num("khugepaged/max_ptes_swap"),
- .max_ptes_shared = read_num("khugepaged/max_ptes_shared"),
- .pages_to_scan = read_num("khugepaged/pages_to_scan"),
- };
if (file_ops && finfo.type == VMA_FILE)
- saved_settings.read_ahead_kb =
- _read_num(finfo.dev_queue_read_ahead_path);
+ thp_set_read_ahead_path(finfo.dev_queue_read_ahead_path);
+ thp_save_settings();

success("OK");

@@ -798,7 +496,7 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
struct mem_ops *ops, bool expect)
{
int ret;
- struct settings settings = *current_settings();
+ struct thp_settings settings = *thp_current_settings();

printf("%s...", msg);

@@ -808,7 +506,7 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
*/
settings.thp_enabled = THP_NEVER;
settings.shmem_enabled = SHMEM_NEVER;
- push_settings(&settings);
+ thp_push_settings(&settings);

/* Clear VM_NOHUGEPAGE */
madvise(p, nr_hpages * hpage_pmd_size, MADV_HUGEPAGE);
@@ -820,7 +518,7 @@ static void __madvise_collapse(const char *msg, char *p, int nr_hpages,
else
success("OK");

- pop_settings();
+ thp_pop_settings();
}

static void madvise_collapse(const char *msg, char *p, int nr_hpages,
@@ -850,13 +548,13 @@ static bool wait_for_scan(const char *msg, char *p, int nr_hpages,
madvise(p, nr_hpages * hpage_pmd_size, MADV_HUGEPAGE);

/* Wait until the second full_scan completed */
- full_scans = read_num("khugepaged/full_scans") + 2;
+ full_scans = thp_read_num("khugepaged/full_scans") + 2;

printf("%s...", msg);
while (timeout--) {
if (ops->check_huge(p, nr_hpages))
break;
- if (read_num("khugepaged/full_scans") >= full_scans)
+ if (thp_read_num("khugepaged/full_scans") >= full_scans)
break;
printf(".");
usleep(TICK);
@@ -911,11 +609,11 @@ static bool is_tmpfs(struct mem_ops *ops)

static void alloc_at_fault(void)
{
- struct settings settings = *current_settings();
+ struct thp_settings settings = *thp_current_settings();
char *p;

settings.thp_enabled = THP_ALWAYS;
- push_settings(&settings);
+ thp_push_settings(&settings);

p = alloc_mapping(1);
*p = 1;
@@ -925,7 +623,7 @@ static void alloc_at_fault(void)
else
fail("Fail");

- pop_settings();
+ thp_pop_settings();

madvise(p, page_size, MADV_DONTNEED);
printf("Split huge PMD on MADV_DONTNEED...");
@@ -973,11 +671,11 @@ static void collapse_single_pte_entry(struct collapse_context *c, struct mem_ops
static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *ops)
{
int max_ptes_none = hpage_pmd_nr / 2;
- struct settings settings = *current_settings();
+ struct thp_settings settings = *thp_current_settings();
void *p;

settings.khugepaged.max_ptes_none = max_ptes_none;
- push_settings(&settings);
+ thp_push_settings(&settings);

p = ops->setup_area(1);

@@ -1002,7 +700,7 @@ static void collapse_max_ptes_none(struct collapse_context *c, struct mem_ops *o
}
skip:
ops->cleanup_area(p, hpage_pmd_size);
- pop_settings();
+ thp_pop_settings();
}

static void collapse_swapin_single_pte(struct collapse_context *c, struct mem_ops *ops)
@@ -1033,7 +731,7 @@ static void collapse_swapin_single_pte(struct collapse_context *c, struct mem_op

static void collapse_max_ptes_swap(struct collapse_context *c, struct mem_ops *ops)
{
- int max_ptes_swap = read_num("khugepaged/max_ptes_swap");
+ int max_ptes_swap = thp_read_num("khugepaged/max_ptes_swap");
void *p;

p = ops->setup_area(1);
@@ -1250,11 +948,11 @@ static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *o
fail("Fail");
ops->fault(p, 0, page_size);

- write_num("khugepaged/max_ptes_shared", hpage_pmd_nr - 1);
+ thp_write_num("khugepaged/max_ptes_shared", hpage_pmd_nr - 1);
c->collapse("Collapse PTE table full of compound pages in child",
p, 1, ops, true);
- write_num("khugepaged/max_ptes_shared",
- current_settings()->khugepaged.max_ptes_shared);
+ thp_write_num("khugepaged/max_ptes_shared",
+ thp_current_settings()->khugepaged.max_ptes_shared);

validate_memory(p, 0, hpage_pmd_size);
ops->cleanup_area(p, hpage_pmd_size);
@@ -1275,7 +973,7 @@ static void collapse_fork_compound(struct collapse_context *c, struct mem_ops *o

static void collapse_max_ptes_shared(struct collapse_context *c, struct mem_ops *ops)
{
- int max_ptes_shared = read_num("khugepaged/max_ptes_shared");
+ int max_ptes_shared = thp_read_num("khugepaged/max_ptes_shared");
int wstatus;
void *p;

@@ -1443,7 +1141,7 @@ static void parse_test_type(int argc, const char **argv)

int main(int argc, const char **argv)
{
- struct settings default_settings = {
+ struct thp_settings default_settings = {
.thp_enabled = THP_MADVISE,
.thp_defrag = THP_DEFRAG_ALWAYS,
.shmem_enabled = SHMEM_ADVISE,
@@ -1484,7 +1182,7 @@ int main(int argc, const char **argv)
default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;

save_settings();
- push_settings(&default_settings);
+ thp_push_settings(&default_settings);

alloc_at_fault();

diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
new file mode 100644
index 000000000000..5e8ec792cac7
--- /dev/null
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "thp_settings.h"
+
+#define THP_SYSFS "/sys/kernel/mm/transparent_hugepage/"
+#define MAX_SETTINGS_DEPTH 4
+static struct thp_settings settings_stack[MAX_SETTINGS_DEPTH];
+static int settings_index;
+static struct thp_settings saved_settings;
+static char dev_queue_read_ahead_path[PATH_MAX];
+
+static const char * const thp_enabled_strings[] = {
+ "always",
+ "madvise",
+ "never",
+ NULL
+};
+
+static const char * const thp_defrag_strings[] = {
+ "always",
+ "defer",
+ "defer+madvise",
+ "madvise",
+ "never",
+ NULL
+};
+
+static const char * const shmem_enabled_strings[] = {
+ "always",
+ "within_size",
+ "advise",
+ "never",
+ "deny",
+ "force",
+ NULL
+};
+
+int read_file(const char *path, char *buf, size_t buflen)
+{
+ int fd;
+ ssize_t numread;
+
+ fd = open(path, O_RDONLY);
+ if (fd == -1)
+ return 0;
+
+ numread = read(fd, buf, buflen - 1);
+ if (numread < 1) {
+ close(fd);
+ return 0;
+ }
+
+ buf[numread] = '\0';
+ close(fd);
+
+ return (unsigned int) numread;
+}
+
+int write_file(const char *path, const char *buf, size_t buflen)
+{
+ int fd;
+ ssize_t numwritten;
+
+ fd = open(path, O_WRONLY);
+ if (fd == -1) {
+ printf("open(%s)\n", path);
+ exit(EXIT_FAILURE);
+ return 0;
+ }
+
+ numwritten = write(fd, buf, buflen - 1);
+ close(fd);
+ if (numwritten < 1) {
+ printf("write(%s)\n", buf);
+ exit(EXIT_FAILURE);
+ return 0;
+ }
+
+ return (unsigned int) numwritten;
+}
+
+const unsigned long read_num(const char *path)
+{
+ char buf[21];
+
+ if (read_file(path, buf, sizeof(buf)) < 0) {
+ perror("read_file()");
+ exit(EXIT_FAILURE);
+ }
+
+ return strtoul(buf, NULL, 10);
+}
+
+void write_num(const char *path, unsigned long num)
+{
+ char buf[21];
+
+ sprintf(buf, "%ld", num);
+ if (!write_file(path, buf, strlen(buf) + 1)) {
+ perror(path);
+ exit(EXIT_FAILURE);
+ }
+}
+
+int thp_read_string(const char *name, const char * const strings[])
+{
+ char path[PATH_MAX];
+ char buf[256];
+ char *c;
+ int ret;
+
+ ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+ if (ret >= PATH_MAX) {
+ printf("%s: Pathname is too long\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+
+ if (!read_file(path, buf, sizeof(buf))) {
+ perror(path);
+ exit(EXIT_FAILURE);
+ }
+
+ c = strchr(buf, '[');
+ if (!c) {
+ printf("%s: Parse failure\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+
+ c++;
+ memmove(buf, c, sizeof(buf) - (c - buf));
+
+ c = strchr(buf, ']');
+ if (!c) {
+ printf("%s: Parse failure\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+ *c = '\0';
+
+ ret = 0;
+ while (strings[ret]) {
+ if (!strcmp(strings[ret], buf))
+ return ret;
+ ret++;
+ }
+
+ printf("Failed to parse %s\n", name);
+ exit(EXIT_FAILURE);
+}
+
+void thp_write_string(const char *name, const char *val)
+{
+ char path[PATH_MAX];
+ int ret;
+
+ ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+ if (ret >= PATH_MAX) {
+ printf("%s: Pathname is too long\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+
+ if (!write_file(path, val, strlen(val) + 1)) {
+ perror(path);
+ exit(EXIT_FAILURE);
+ }
+}
+
+const unsigned long thp_read_num(const char *name)
+{
+ char path[PATH_MAX];
+ int ret;
+
+ ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+ if (ret >= PATH_MAX) {
+ printf("%s: Pathname is too long\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+ return read_num(path);
+}
+
+void thp_write_num(const char *name, unsigned long num)
+{
+ char path[PATH_MAX];
+ int ret;
+
+ ret = snprintf(path, PATH_MAX, THP_SYSFS "%s", name);
+ if (ret >= PATH_MAX) {
+ printf("%s: Pathname is too long\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+ write_num(path, num);
+}
+
+void thp_read_settings(struct thp_settings *settings)
+{
+ *settings = (struct thp_settings) {
+ .thp_enabled = thp_read_string("enabled", thp_enabled_strings),
+ .thp_defrag = thp_read_string("defrag", thp_defrag_strings),
+ .shmem_enabled =
+ thp_read_string("shmem_enabled", shmem_enabled_strings),
+ .use_zero_page = thp_read_num("use_zero_page"),
+ };
+ settings->khugepaged = (struct khugepaged_settings) {
+ .defrag = thp_read_num("khugepaged/defrag"),
+ .alloc_sleep_millisecs =
+ thp_read_num("khugepaged/alloc_sleep_millisecs"),
+ .scan_sleep_millisecs =
+ thp_read_num("khugepaged/scan_sleep_millisecs"),
+ .max_ptes_none = thp_read_num("khugepaged/max_ptes_none"),
+ .max_ptes_swap = thp_read_num("khugepaged/max_ptes_swap"),
+ .max_ptes_shared = thp_read_num("khugepaged/max_ptes_shared"),
+ .pages_to_scan = thp_read_num("khugepaged/pages_to_scan"),
+ };
+ if (dev_queue_read_ahead_path[0])
+ settings->read_ahead_kb = read_num(dev_queue_read_ahead_path);
+}
+
+void thp_write_settings(struct thp_settings *settings)
+{
+ struct khugepaged_settings *khugepaged = &settings->khugepaged;
+
+ thp_write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
+ thp_write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
+ thp_write_string("shmem_enabled",
+ shmem_enabled_strings[settings->shmem_enabled]);
+ thp_write_num("use_zero_page", settings->use_zero_page);
+
+ thp_write_num("khugepaged/defrag", khugepaged->defrag);
+ thp_write_num("khugepaged/alloc_sleep_millisecs",
+ khugepaged->alloc_sleep_millisecs);
+ thp_write_num("khugepaged/scan_sleep_millisecs",
+ khugepaged->scan_sleep_millisecs);
+ thp_write_num("khugepaged/max_ptes_none", khugepaged->max_ptes_none);
+ thp_write_num("khugepaged/max_ptes_swap", khugepaged->max_ptes_swap);
+ thp_write_num("khugepaged/max_ptes_shared", khugepaged->max_ptes_shared);
+ thp_write_num("khugepaged/pages_to_scan", khugepaged->pages_to_scan);
+
+ if (dev_queue_read_ahead_path[0])
+ write_num(dev_queue_read_ahead_path, settings->read_ahead_kb);
+}
+
+struct thp_settings *thp_current_settings(void)
+{
+ if (!settings_index) {
+ printf("Fail: No settings set");
+ exit(EXIT_FAILURE);
+ }
+ return settings_stack + settings_index - 1;
+}
+
+void thp_push_settings(struct thp_settings *settings)
+{
+ if (settings_index >= MAX_SETTINGS_DEPTH) {
+ printf("Fail: Settings stack exceeded");
+ exit(EXIT_FAILURE);
+ }
+ settings_stack[settings_index++] = *settings;
+ thp_write_settings(thp_current_settings());
+}
+
+void thp_pop_settings(void)
+{
+ if (settings_index <= 0) {
+ printf("Fail: Settings stack empty");
+ exit(EXIT_FAILURE);
+ }
+ --settings_index;
+ thp_write_settings(thp_current_settings());
+}
+
+void thp_restore_settings(void)
+{
+ thp_write_settings(&saved_settings);
+}
+
+void thp_save_settings(void)
+{
+ thp_read_settings(&saved_settings);
+}
+
+void thp_set_read_ahead_path(char *path)
+{
+ if (!path) {
+ dev_queue_read_ahead_path[0] = '\0';
+ return;
+ }
+
+ strncpy(dev_queue_read_ahead_path, path,
+ sizeof(dev_queue_read_ahead_path));
+ dev_queue_read_ahead_path[sizeof(dev_queue_read_ahead_path) - 1] = '\0';
+}
diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
new file mode 100644
index 000000000000..ff3d98c30617
--- /dev/null
+++ b/tools/testing/selftests/mm/thp_settings.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __THP_SETTINGS_H__
+#define __THP_SETTINGS_H__
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+enum thp_enabled {
+ THP_ALWAYS,
+ THP_MADVISE,
+ THP_NEVER,
+};
+
+enum thp_defrag {
+ THP_DEFRAG_ALWAYS,
+ THP_DEFRAG_DEFER,
+ THP_DEFRAG_DEFER_MADVISE,
+ THP_DEFRAG_MADVISE,
+ THP_DEFRAG_NEVER,
+};
+
+enum shmem_enabled {
+ SHMEM_ALWAYS,
+ SHMEM_WITHIN_SIZE,
+ SHMEM_ADVISE,
+ SHMEM_NEVER,
+ SHMEM_DENY,
+ SHMEM_FORCE,
+};
+
+struct khugepaged_settings {
+ bool defrag;
+ unsigned int alloc_sleep_millisecs;
+ unsigned int scan_sleep_millisecs;
+ unsigned int max_ptes_none;
+ unsigned int max_ptes_swap;
+ unsigned int max_ptes_shared;
+ unsigned long pages_to_scan;
+};
+
+struct thp_settings {
+ enum thp_enabled thp_enabled;
+ enum thp_defrag thp_defrag;
+ enum shmem_enabled shmem_enabled;
+ bool use_zero_page;
+ struct khugepaged_settings khugepaged;
+ unsigned long read_ahead_kb;
+};
+
+int read_file(const char *path, char *buf, size_t buflen);
+int write_file(const char *path, const char *buf, size_t buflen);
+const unsigned long read_num(const char *path);
+void write_num(const char *path, unsigned long num);
+
+int thp_read_string(const char *name, const char * const strings[]);
+void thp_write_string(const char *name, const char *val);
+const unsigned long thp_read_num(const char *name);
+void thp_write_num(const char *name, unsigned long num);
+
+void thp_write_settings(struct thp_settings *settings);
+void thp_read_settings(struct thp_settings *settings);
+struct thp_settings *thp_current_settings(void);
+void thp_push_settings(struct thp_settings *settings);
+void thp_pop_settings(void);
+void thp_restore_settings(void);
+void thp_save_settings(void);
+
+void thp_set_read_ahead_path(char *path);
+
+#endif /* __THP_SETTINGS_H__ */
--
2.25.1