On 2024/10/29 08:13, Maíra Canal wrote:
Add a new kernel command line to control the hugepage allocation policy
for the internal shmem mount, ``transparent_hugepage_shmem``. The
parameter is similar to ``transparent_hugepage`` and has the following
format:
transparent_hugepage_shmem=<policy>
where ``<policy>`` is one of the seven valid policies available for
shmem.
By configuring the default hugepage allocation policy for the internal
shmem mount, applications that use shmem, such as the DRM GEM objects,
can take advantage of mTHP before it's been configured through sysfs.
Just out of curiosity, do you have any performance benefit data when
using mTHP for DRM GEM objects?
Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx>
---
.../admin-guide/kernel-parameters.txt | 7 +++
Documentation/admin-guide/mm/transhuge.rst | 6 +++
mm/shmem.c | 53 +++++++++++++++----
3 files changed, 57 insertions(+), 9 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1666576acc0e..acabb04d0dd4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6926,6 +6926,13 @@
See Documentation/admin-guide/mm/transhuge.rst
for more details.
+ transparent_hugepage_shmem= [KNL]
+ Format: [always|within_size|advise|never|deny|force]
+ Can be used to control the hugepage allocation policy for
+ the internal shmem mount.
+ See Documentation/admin-guide/mm/transhuge.rst
+ for more details.
+
trusted.source= [KEYS]
Format: <string>
This parameter identifies the trust source as a backend
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 745055c3dc09..9b5b02c4d1ab 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -326,6 +326,12 @@ PMD_ORDER THP policy will be overridden. If the policy for PMD_ORDER
is not defined within a valid ``thp_anon``, its policy will default to
``never``.
+Similarly to ``transparent_hugepage``, you can control the hugepage
+allocation policy for the internal shmem mount by using the kernel parameter
+``transparent_hugepage_shmem=<policy>``, where ``<policy>`` is one of the
+seven valid policies for shmem (``always``, ``within_size``, ``advise``,
+``never``, ``deny``, and ``force``).
+
Hugepages in tmpfs/shmem
========================
diff --git a/mm/shmem.c b/mm/shmem.c
index 44282a296c33..26c1eb1b4b1d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -582,7 +582,6 @@ static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
}
}
-#if defined(CONFIG_SYSFS)
static int shmem_parse_huge(const char *str)
{
if (!strcmp(str, "never"))
@@ -599,7 +598,6 @@ static int shmem_parse_huge(const char *str)
return SHMEM_HUGE_FORCE;
return -EINVAL;
}
-#endif
#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
static const char *shmem_format_huge(int huge)
@@ -624,6 +622,20 @@ static const char *shmem_format_huge(int huge)
}
#endif
+static int shmem_valid_huge(int huge)
+{
+ if (!has_transparent_hugepage() &&
+ huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
+ return -EINVAL;
+
+ /* Do not override huge allocation policy with non-PMD sized mTHP */
+ if (huge == SHMEM_HUGE_FORCE &&
+ huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
+ return -EINVAL;
+
+ return 0;
+}
+
static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
struct shrink_control *sc, unsigned long nr_to_free)
{
@@ -5070,14 +5082,10 @@ static ssize_t shmem_enabled_store(struct kobject *kobj,
huge = shmem_parse_huge(tmp);
if (huge == -EINVAL)
return -EINVAL;
- if (!has_transparent_hugepage() &&
- huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
- return -EINVAL;
- /* Do not override huge allocation policy with non-PMD sized mTHP */
- if (huge == SHMEM_HUGE_FORCE &&
- huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
- return -EINVAL;
+ err = shmem_valid_huge(huge);
+ if (err)
+ return err;
shmem_huge = huge;
if (shmem_huge > SHMEM_HUGE_DENY)
@@ -5174,6 +5182,33 @@ struct kobj_attribute thpsize_shmem_enabled_attr =
__ATTR(shmem_enabled, 0644, thpsize_shmem_enabled_show, thpsize_shmem_enabled_store);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
+
+static int __init setup_transparent_hugepage_shmem(char *str)
+{
+ int huge, ret = 0;
+
+ if (!str)
+ goto out;
+
+ huge = shmem_parse_huge(str);
+ if (huge == -EINVAL)
+ goto out;
Looks better. But shmem_parse_huge() is also a common part, and what I
am thinking is below:
diff --git a/mm/shmem.c b/mm/shmem.c
index f8b8b1ad2631..646d8943950a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -629,24 +629,39 @@ static unsigned int
shmem_huge_global_enabled(struct inode *inode, pgoff_t index
}
}
-#if defined(CONFIG_SYSFS)
static int shmem_parse_huge(const char *str)
{
+ int huge;
+
+ if (!str)
+ return -EINVAL;
+
if (!strcmp(str, "never"))
- return SHMEM_HUGE_NEVER;
- if (!strcmp(str, "always"))
- return SHMEM_HUGE_ALWAYS;
- if (!strcmp(str, "within_size"))
- return SHMEM_HUGE_WITHIN_SIZE;
- if (!strcmp(str, "advise"))
- return SHMEM_HUGE_ADVISE;
- if (!strcmp(str, "deny"))
- return SHMEM_HUGE_DENY;
- if (!strcmp(str, "force"))
- return SHMEM_HUGE_FORCE;
- return -EINVAL;
+ huge = SHMEM_HUGE_NEVER;
+ else if (!strcmp(str, "always"))
+ huge = SHMEM_HUGE_ALWAYS;
+ else if (!strcmp(str, "within_size"))
+ huge = SHMEM_HUGE_WITHIN_SIZE;
+ else if (!strcmp(str, "advise"))
+ huge = SHMEM_HUGE_ADVISE;
+ else if (!strcmp(str, "deny"))
+ huge = SHMEM_HUGE_DENY;
+ else if (!strcmp(str, "force"))
+ huge = SHMEM_HUGE_FORCE;
+ else
+ return -EINVAL;
+
+ if (!has_transparent_hugepage() &&
+ huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
+ return -EINVAL;
+
+ /* Do not override huge allocation policy with non-PMD sized mTHP */
+ if (huge == SHMEM_HUGE_FORCE &&
+ huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
+ return -EINVAL;
+
+ return huge;
}
-#endif
#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
static const char *shmem_format_huge(int huge)
@@ -5104,16 +5119,8 @@ static ssize_t shmem_enabled_store(struct kobject
*kobj,
tmp[count - 1] = '\0';
huge = shmem_parse_huge(tmp);
- if (huge == -EINVAL)
- return -EINVAL;
- if (!has_transparent_hugepage() &&
- huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
- return -EINVAL;
-
- /* Do not override huge allocation policy with non-PMD sized mTHP */
- if (huge == SHMEM_HUGE_FORCE &&
- huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
- return -EINVAL;
+ if (huge < 0)
+ return huge;
shmem_huge = huge;
if (shmem_huge > SHMEM_HUGE_DENY)
@@ -5210,6 +5217,25 @@ struct kobj_attribute thpsize_shmem_enabled_attr =
__ATTR(shmem_enabled, 0644, thpsize_shmem_enabled_show,
thpsize_shmem_enabled_store);
#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
+#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
+
+static int __init setup_transparent_hugepage_shmem(char *str)
+{
+ int huge;
+
+ huge = shmem_parse_huge(str);
+ if (huge < 0) {
+ pr_warn("transparent_hugepage_shmem= cannot parse,
ignored\n");
+ return 0;
+ }
+
+ shmem_huge = huge;
+ return 1;
+}
+__setup("transparent_hugepage_shmem=", setup_transparent_hugepage_shmem);
+
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+
#else /* !CONFIG_SHMEM */
/*
