[PATCH v3] mm: Override mTHP "enabled" defaults at kernel cmdline

[PATCH v3] mm: Override mTHP "enabled" defaults at kernel cmdline

[Barry Song]

From: Ryan Roberts <ryan.roberts@arm.com>

Add thp_anon= cmdline parameter to allow specifying the default
enablement of each supported anon THP size. The parameter accepts the
following format and can be provided multiple times to configure each
size:

thp_anon=<size>,<size>[KMG]:<value>;<size>-<size>[KMG]:<value>

An example:

thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never

See Documentation/admin-guide/mm/transhuge.rst for more details.

Configuring the defaults at boot time is useful to allow early user
space to take advantage of mTHP before its been configured through
sysfs.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Co-developed-by: Barry Song <v-songbaohua@oppo.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
-v3:
  * support formats as below, Per David's suggestion
    thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
  * document the relationship between transparent_hugepage
    and thp_anon better, Per David;
  *
  Hi Baolin,
  I am taking your Reviewed-by because the code has
  changed quite a lot.

 .../admin-guide/kernel-parameters.txt         |   9 ++
 Documentation/admin-guide/mm/transhuge.rst    |  37 ++++--
 mm/huge_memory.c                              | 112 +++++++++++++++++-
 3 files changed, 150 insertions(+), 8 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f0057bac20fb..d0d141d50638 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -6629,6 +6629,15 @@
 			<deci-seconds>: poll all this frequency
 			0: no polling (default)
 
+	thp_anon=	[KNL]
+			Format: <size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>
+			state is one of "always", "madvise", "never" or "inherit".
+			Can be used to control the default behavior of the
+			system with respect to anonymous transparent hugepages.
+			Can be used multiple times for multiple anon THP sizes.
+			See Documentation/admin-guide/mm/transhuge.rst for more
+			details.
+
 	threadirqs	[KNL,EARLY]
 			Force threading of all interrupt handlers except those
 			marked explicitly IRQF_NO_THREAD.
diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
index 7072469de8a8..528e1a19d63f 100644
--- a/Documentation/admin-guide/mm/transhuge.rst
+++ b/Documentation/admin-guide/mm/transhuge.rst
@@ -284,13 +284,36 @@ that THP is shared. Exceeding the number would block the collapse::
 
 A higher value may increase memory footprint for some workloads.
 
-Boot parameter
-==============
-
-You can change the sysfs boot time defaults of Transparent Hugepage
-Support by passing the parameter ``transparent_hugepage=always`` or
-``transparent_hugepage=madvise`` or ``transparent_hugepage=never``
-to the kernel command line.
+Boot parameters
+===============
+
+You can change the sysfs boot time default for the top-level "enabled"
+control by passing the parameter ``transparent_hugepage=always`` or
+``transparent_hugepage=madvise`` or ``transparent_hugepage=never`` to the
+kernel command line.
+
+Alternatively, each supported anonymous THP size can be controlled by
+passing ``thp_anon=<size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>``,
+where ``<size>`` is the THP size and ``<state>`` is one of ``always``,
+``madvise``, ``never`` or ``inherit``.
+
+For example, the following will set 16K, 32K, 64K THP to ``always``,
+set 128K, 512K to ``inherit``, set 256K to ``madvise`` and 1M, 2M
+to ``never``::
+
+	thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
+
+``thp_anon=`` may be specified multiple times to configure all THP sizes as
+required. If ``thp_anon=`` is specified at least once, any anon THP sizes
+not explicitly configured on the command line are implicitly set to
+``never``.
+
+``transparent_hugepage`` setting only affects the global toggle. If
+``thp_anon`` is not specified, PMD_ORDER THP will default to ``inherit``.
+However, if a valid ``thp_anon`` setting is provided by the user, the
+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``.
 
 Hugepages in tmpfs/shmem
 ========================
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 1a12c011e2df..e8eeb8111f6e 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -81,6 +81,7 @@ unsigned long huge_zero_pfn __read_mostly = ~0UL;
 unsigned long huge_anon_orders_always __read_mostly;
 unsigned long huge_anon_orders_madvise __read_mostly;
 unsigned long huge_anon_orders_inherit __read_mostly;
+static bool anon_orders_configured;
 
 unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
 					 unsigned long vm_flags,
@@ -737,7 +738,10 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
 	 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time
 	 * constant so we have to do this here.
 	 */
-	huge_anon_orders_inherit = BIT(PMD_ORDER);
+	if (!anon_orders_configured) {
+		huge_anon_orders_inherit = BIT(PMD_ORDER);
+		anon_orders_configured = true;
+	}
 
 	*hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
 	if (unlikely(!*hugepage_kobj)) {
@@ -922,6 +926,112 @@ static int __init setup_transparent_hugepage(char *str)
 }
 __setup("transparent_hugepage=", setup_transparent_hugepage);
 
+static inline int get_order_from_str(const char *size_str)
+{
+	unsigned long size;
+	char *endptr;
+	int order;
+
+	size = memparse(size_str, &endptr);
+	order = fls(size >> PAGE_SHIFT) - 1;
+	if ((1 << order) & ~THP_ORDERS_ALL_ANON) {
+		pr_err("invalid size %s order %d in thp_anon boot parameter\n",
+			size_str, order);
+		return -EINVAL;
+	}
+
+	return order;
+}
+
+static inline void set_bits(unsigned long *var, int start, int end)
+{
+	int i;
+
+	for (i = start; i <= end; i++)
+		set_bit(i, var);
+}
+
+static inline void clear_bits(unsigned long *var, int start, int end)
+{
+	int i;
+
+	for (i = start; i <= end; i++)
+		clear_bit(i, var);
+}
+
+static char str_dup[PAGE_SIZE] __meminitdata;
+static int __init setup_thp_anon(char *str)
+{
+	char *token, *range, *policy, *subtoken;
+	unsigned long always, inherit, madvise;
+	char *start_size, *end_size;
+	int start, end;
+	char *p;
+
+	if (!str || strlen(str) + 1 > PAGE_SIZE)
+		goto err;
+	strcpy(str_dup, str);
+
+	always = huge_anon_orders_always;
+	madvise = huge_anon_orders_madvise;
+	inherit = huge_anon_orders_inherit;
+	p = str_dup;
+	while ((token = strsep(&p, ";")) != NULL) {
+		range = strsep(&token, ":");
+		policy = token;
+
+		if (!policy)
+			goto err;
+
+		while ((subtoken = strsep(&range, ",")) != NULL) {
+			if (strchr(subtoken, '-')) {
+				start_size = strsep(&subtoken, "-");
+				end_size = subtoken;
+
+				start = get_order_from_str(start_size);
+				end = get_order_from_str(end_size);
+			} else {
+				start = end = get_order_from_str(subtoken);
+			}
+
+			if (start < 0 || end < 0 || start > end)
+				goto err;
+
+			if (!strcmp(policy, "always")) {
+				set_bits(&always, start, end);
+				clear_bits(&inherit, start, end);
+				clear_bits(&madvise, start, end);
+			} else if (!strcmp(policy, "madvise")) {
+				set_bits(&madvise, start, end);
+				clear_bits(&inherit, start, end);
+				clear_bits(&always, start, end);
+			} else if (!strcmp(policy, "inherit")) {
+				set_bits(&inherit, start, end);
+				clear_bits(&madvise, start, end);
+				clear_bits(&always, start, end);
+			} else if (!strcmp(policy, "never")) {
+				clear_bits(&inherit, start, end);
+				clear_bits(&madvise, start, end);
+				clear_bits(&always, start, end);
+			} else {
+				pr_err("invalid policy %s in thp_anon boot parameter\n", policy);
+				goto err;
+			}
+		}
+	}
+
+	huge_anon_orders_always = always;
+	huge_anon_orders_madvise = madvise;
+	huge_anon_orders_inherit = inherit;
+	anon_orders_configured = true;
+	return 1;
+
+err:
+	pr_warn("thp_anon=%s: cannot parse, ignored\n", str);
+	return 0;
+}
+__setup("thp_anon=", setup_thp_anon);
+
 pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma)
 {
 	if (likely(vma->vm_flags & VM_WRITE))
-- 
2.34.1

Re: [PATCH v3] mm: Override mTHP "enabled" defaults at kernel cmdline

[David Hildenbrand]

On 12.08.24 12:24, Barry Song wrote:
> From: Ryan Roberts <ryan.roberts@arm.com>
> 
> Add thp_anon= cmdline parameter to allow specifying the default
> enablement of each supported anon THP size. The parameter accepts the
> following format and can be provided multiple times to configure each
> size:
> 
> thp_anon=<size>,<size>[KMG]:<value>;<size>-<size>[KMG]:<value>
> 
> An example:
> 
> thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
> 
> See Documentation/admin-guide/mm/transhuge.rst for more details.
> 
> Configuring the defaults at boot time is useful to allow early user
> space to take advantage of mTHP before its been configured through
> sysfs.
> 
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> Co-developed-by: Barry Song <v-songbaohua@oppo.com>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
> -v3:
>    * support formats as below, Per David's suggestion
>      thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
>    * document the relationship between transparent_hugepage
>      and thp_anon better, Per David;
>    *
>    Hi Baolin,
>    I am taking your Reviewed-by because the code has
>    changed quite a lot.
> 
>   .../admin-guide/kernel-parameters.txt         |   9 ++
>   Documentation/admin-guide/mm/transhuge.rst    |  37 ++++--
>   mm/huge_memory.c                              | 112 +++++++++++++++++-
>   3 files changed, 150 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index f0057bac20fb..d0d141d50638 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -6629,6 +6629,15 @@
>   			<deci-seconds>: poll all this frequency
>   			0: no polling (default)
>   
> +	thp_anon=	[KNL]
> +			Format: <size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>
> +			state is one of "always", "madvise", "never" or "inherit".
> +			Can be used to control the default behavior of the
> +			system with respect to anonymous transparent hugepages.
> +			Can be used multiple times for multiple anon THP sizes.
> +			See Documentation/admin-guide/mm/transhuge.rst for more
> +			details.
> +
>   	threadirqs	[KNL,EARLY]
>   			Force threading of all interrupt handlers except those
>   			marked explicitly IRQF_NO_THREAD.
> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst
> index 7072469de8a8..528e1a19d63f 100644
> --- a/Documentation/admin-guide/mm/transhuge.rst
> +++ b/Documentation/admin-guide/mm/transhuge.rst
> @@ -284,13 +284,36 @@ that THP is shared. Exceeding the number would block the collapse::
>   
>   A higher value may increase memory footprint for some workloads.
>   
> -Boot parameter
> -==============
> -
> -You can change the sysfs boot time defaults of Transparent Hugepage
> -Support by passing the parameter ``transparent_hugepage=always`` or
> -``transparent_hugepage=madvise`` or ``transparent_hugepage=never``
> -to the kernel command line.
> +Boot parameters
> +===============
> +
> +You can change the sysfs boot time default for the top-level "enabled"
> +control by passing the parameter ``transparent_hugepage=always`` or
> +``transparent_hugepage=madvise`` or ``transparent_hugepage=never`` to the
> +kernel command line.
> +
> +Alternatively, each supported anonymous THP size can be controlled by
> +passing ``thp_anon=<size>,<size>[KMG]:<state>;<size>-<size>[KMG]:<state>``,
> +where ``<size>`` is the THP size and ``<state>`` is one of ``always``,
> +``madvise``, ``never`` or ``inherit``.
> +
> +For example, the following will set 16K, 32K, 64K THP to ``always``,
> +set 128K, 512K to ``inherit``, set 256K to ``madvise`` and 1M, 2M
> +to ``never``::
> +
> +	thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never
> +
> +``thp_anon=`` may be specified multiple times to configure all THP sizes as
> +required. If ``thp_anon=`` is specified at least once, any anon THP sizes
> +not explicitly configured on the command line are implicitly set to
> +``never``.
> +
> +``transparent_hugepage`` setting only affects the global toggle. If
> +``thp_anon`` is not specified, PMD_ORDER THP will default to ``inherit``.
> +However, if a valid ``thp_anon`` setting is provided by the user, the
> +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``.
>   
>   Hugepages in tmpfs/shmem
>   ========================
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 1a12c011e2df..e8eeb8111f6e 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -81,6 +81,7 @@ unsigned long huge_zero_pfn __read_mostly = ~0UL;
>   unsigned long huge_anon_orders_always __read_mostly;
>   unsigned long huge_anon_orders_madvise __read_mostly;
>   unsigned long huge_anon_orders_inherit __read_mostly;
> +static bool anon_orders_configured;
>   
>   unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
>   					 unsigned long vm_flags,
> @@ -737,7 +738,10 @@ static int __init hugepage_init_sysfs(struct kobject **hugepage_kobj)
>   	 * disable all other sizes. powerpc's PMD_ORDER isn't a compile-time
>   	 * constant so we have to do this here.
>   	 */
> -	huge_anon_orders_inherit = BIT(PMD_ORDER);
> +	if (!anon_orders_configured) {
> +		huge_anon_orders_inherit = BIT(PMD_ORDER);
> +		anon_orders_configured = true;
> +	}
>   
>   	*hugepage_kobj = kobject_create_and_add("transparent_hugepage", mm_kobj);
>   	if (unlikely(!*hugepage_kobj)) {
> @@ -922,6 +926,112 @@ static int __init setup_transparent_hugepage(char *str)
>   }
>   __setup("transparent_hugepage=", setup_transparent_hugepage);
>   
> +static inline int get_order_from_str(const char *size_str)
> +{
> +	unsigned long size;
> +	char *endptr;
> +	int order;
> +
> +	size = memparse(size_str, &endptr);
> +	order = fls(size >> PAGE_SHIFT) - 1;
> +	if ((1 << order) & ~THP_ORDERS_ALL_ANON) {
> +		pr_err("invalid size %s order %d in thp_anon boot parameter\n",
> +			size_str, order);
> +		return -EINVAL;
> +	}
> +
> +	return order;
> +}
> +
> +static inline void set_bits(unsigned long *var, int start, int end)
> +{
> +	int i;
> +
> +	for (i = start; i <= end; i++)
> +		set_bit(i, var);
> +}
> +
> +static inline void clear_bits(unsigned long *var, int start, int end)
> +{
> +	int i;
> +
> +	for (i = start; i <= end; i++)
> +		clear_bit(i, var);
> +}
>

Do we really need atomic set_bit/clear_bit here or would 
__set_bit/__clear_bit be sufficient?

Also, could we use bitmap_set/bitmap_clear here?

-- 
Cheers,

David / dhildenb