[PATCH v8 07/10] selftests/mm: Support multi-size THP interface in thp_settings

Ryan Roberts
2023-12-04T10:21:57Z

Save and restore the new per-size hugepage enabled setting, if available
on the running kernel.

Since the number of per-size directories is not fixed, solve this as
simply as possible by catering for a maximum number in the thp_settings
struct (20). Each array index is the order. The value of THP_NEVER is
changed to 0 so that all of these new settings default to THP_NEVER and
the user only needs to fill in the ones they want to enable.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
tools/testing/selftests/mm/khugepaged.c | 3 ++
tools/testing/selftests/mm/thp_settings.c | 55 ++++++++++++++++++++++-
tools/testing/selftests/mm/thp_settings.h | 11 ++++-
3 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/khugepaged.c b/tools/testing/selftests/mm/khugepaged.c
index b15e7fd70176..7bd3baa9d34b 100644
--- a/tools/testing/selftests/mm/khugepaged.c
+++ b/tools/testing/selftests/mm/khugepaged.c
@@ -1141,6 +1141,7 @@ static void parse_test_type(int argc, const char **argv)

int main(int argc, const char **argv)
{
+ int hpage_pmd_order;
struct thp_settings default_settings = {
.thp_enabled = THP_MADVISE,
.thp_defrag = THP_DEFRAG_ALWAYS,
@@ -1175,11 +1176,13 @@ int main(int argc, const char **argv)
exit(EXIT_FAILURE);
}
hpage_pmd_nr = hpage_pmd_size / page_size;
+ hpage_pmd_order = __builtin_ctz(hpage_pmd_nr);

default_settings.khugepaged.max_ptes_none = hpage_pmd_nr - 1;
default_settings.khugepaged.max_ptes_swap = hpage_pmd_nr / 8;
default_settings.khugepaged.max_ptes_shared = hpage_pmd_nr / 2;
default_settings.khugepaged.pages_to_scan = hpage_pmd_nr * 8;
+ default_settings.hugepages[hpage_pmd_order].enabled = THP_INHERIT;

save_settings();
thp_push_settings(&default_settings);
diff --git a/tools/testing/selftests/mm/thp_settings.c b/tools/testing/selftests/mm/thp_settings.c
index 5e8ec792cac7..a4163438108e 100644
--- a/tools/testing/selftests/mm/thp_settings.c
+++ b/tools/testing/selftests/mm/thp_settings.c
@@ -16,9 +16,10 @@ static struct thp_settings saved_settings;
static char dev_queue_read_ahead_path[PATH_MAX];

static const char * const thp_enabled_strings[] = {
+ "never",
"always",
+ "inherit",
"madvise",
- "never",
NULL
};

@@ -198,6 +199,10 @@ void thp_write_num(const char *name, unsigned long num)

void thp_read_settings(struct thp_settings *settings)
{
+ unsigned long orders = thp_supported_orders();
+ char path[PATH_MAX];
+ int i;
+
*settings = (struct thp_settings) {
.thp_enabled = thp_read_string("enabled", thp_enabled_strings),
.thp_defrag = thp_read_string("defrag", thp_defrag_strings),
@@ -218,11 +223,26 @@ void thp_read_settings(struct thp_settings *settings)
};
if (dev_queue_read_ahead_path[0])
settings->read_ahead_kb = read_num(dev_queue_read_ahead_path);
+
+ for (i = 0; i < NR_ORDERS; i++) {
+ if (!((1 << i) & orders)) {
+ settings->hugepages[i].enabled = THP_NEVER;
+ continue;
+ }
+ snprintf(path, PATH_MAX, "hugepages-%ukB/enabled",
+ (getpagesize() >> 10) << i);
+ settings->hugepages[i].enabled =
+ thp_read_string(path, thp_enabled_strings);
+ }
}

void thp_write_settings(struct thp_settings *settings)
{
struct khugepaged_settings *khugepaged = &settings->khugepaged;
+ unsigned long orders = thp_supported_orders();
+ char path[PATH_MAX];
+ int enabled;
+ int i;

thp_write_string("enabled", thp_enabled_strings[settings->thp_enabled]);
thp_write_string("defrag", thp_defrag_strings[settings->thp_defrag]);
@@ -242,6 +262,15 @@ void thp_write_settings(struct thp_settings *settings)

if (dev_queue_read_ahead_path[0])
write_num(dev_queue_read_ahead_path, settings->read_ahead_kb);
+
+ for (i = 0; i < NR_ORDERS; i++) {
+ if (!((1 << i) & orders))
+ continue;
+ snprintf(path, PATH_MAX, "hugepages-%ukB/enabled",
+ (getpagesize() >> 10) << i);
+ enabled = settings->hugepages[i].enabled;
+ thp_write_string(path, thp_enabled_strings[enabled]);
+ }
}

struct thp_settings *thp_current_settings(void)
@@ -294,3 +323,27 @@ void thp_set_read_ahead_path(char *path)
sizeof(dev_queue_read_ahead_path));
dev_queue_read_ahead_path[sizeof(dev_queue_read_ahead_path) - 1] = '\0';
}
+
+unsigned long thp_supported_orders(void)
+{
+ unsigned long orders = 0;
+ char path[PATH_MAX];
+ char buf[256];
+ int ret;
+ int i;
+
+ for (i = 0; i < NR_ORDERS; i++) {
+ ret = snprintf(path, PATH_MAX, THP_SYSFS "hugepages-%ukB/enabled",
+ (getpagesize() >> 10) << i);
+ if (ret >= PATH_MAX) {
+ printf("%s: Pathname is too long\n", __func__);
+ exit(EXIT_FAILURE);
+ }
+
+ ret = read_file(path, buf, sizeof(buf));
+ if (ret)
+ orders |= 1UL << i;
+ }
+
+ return orders;
+}
diff --git a/tools/testing/selftests/mm/thp_settings.h b/tools/testing/selftests/mm/thp_settings.h
index ff3d98c30617..71cbff05f4c7 100644
--- a/tools/testing/selftests/mm/thp_settings.h
+++ b/tools/testing/selftests/mm/thp_settings.h
@@ -7,9 +7,10 @@
#include <stdint.h>

enum thp_enabled {
+ THP_NEVER,
THP_ALWAYS,
+ THP_INHERIT,
THP_MADVISE,
- THP_NEVER,
};

enum thp_defrag {
@@ -29,6 +30,12 @@ enum shmem_enabled {
SHMEM_FORCE,
};

+#define NR_ORDERS 20
+
+struct hugepages_settings {
+ enum thp_enabled enabled;
+};
+
struct khugepaged_settings {
bool defrag;
unsigned int alloc_sleep_millisecs;
@@ -46,6 +53,7 @@ struct thp_settings {
bool use_zero_page;
struct khugepaged_settings khugepaged;
unsigned long read_ahead_kb;
+ struct hugepages_settings hugepages[NR_ORDERS];
};

int read_file(const char *path, char *buf, size_t buflen);
@@ -67,5 +75,6 @@ void thp_restore_settings(void);
void thp_save_settings(void);

void thp_set_read_ahead_path(char *path);
+unsigned long thp_supported_orders(void);

#endif /* __THP_SETTINGS_H__ */
--
2.25.1