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Message-ID: <e36e4157-ba42-432f-aebe-7c2c36917e57@redhat.com>
Date: Tue, 20 Aug 2024 09:53:13 +0200
From: David Hildenbrand <david@...hat.com>
To: Barry Song <21cnbao@...il.com>, akpm@...ux-foundation.org,
linux-mm@...ck.org
Cc: baohua@...nel.org, baolin.wang@...ux.alibaba.com, corbet@....net,
ioworker0@...il.com, linux-kernel@...r.kernel.org, ryan.roberts@....com,
v-songbaohua@...o.com
Subject: Re: [PATCH v5] mm: override mTHP "enabled" defaults at kernel cmdline
On 17.08.24 06:55, Barry Song wrote:
> From: Ryan Roberts <ryan.roberts@....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@....com>
> Co-developed-by: Barry Song <v-songbaohua@...o.com>
> Signed-off-by: Barry Song <v-songbaohua@...o.com>
> Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> Tested-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Jonathan Corbet <corbet@....net>
> Cc: Lance Yang <ioworker0@...il.com>
Acked-by: David Hildenbrand <david@...hat.com>
Some nits:
> ---
> -v5:
> * collect Baolin's reviewed-by and tested-by tags, thanks!
> * use get_order and check size is power 2, David, Baolin;
> * use proper __initdata
>
> .../admin-guide/kernel-parameters.txt | 9 ++
> Documentation/admin-guide/mm/transhuge.rst | 38 +++++--
> mm/huge_memory.c | 100 +++++++++++++++++-
> 3 files changed, 139 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
s/Can be used to control/Control/
> + 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 60522f49178b..4468851b6ecb 100644
> --- a/Documentation/admin-guide/mm/transhuge.rst
> +++ b/Documentation/admin-guide/mm/transhuge.rst
> @@ -284,13 +284,37 @@ that THP is shared. Exceeding the number would block the collapse::
>
> A higher value may increase memory footprint for some workloads.
[...]
> unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma,
> unsigned long vm_flags,
> @@ -756,7 +757,10 @@ 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)) {
> @@ -941,6 +945,100 @@ 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);
> +
> + if (!is_power_of_2(size))
> + goto err;
> + order = get_order(size);
> + if ((1 << order) & ~THP_ORDERS_ALL_ANON)
Could do
"if (BIT(order) & ~THP_ORDERS_ALL_ANON)"
> + goto err;
> +
> + return order;
> +err:
> + pr_err("invalid size %s in thp_anon boot parameter\n", size_str);
> + return -EINVAL;
> +}
> +
> +static char str_dup[PAGE_SIZE] __initdata;
> +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, nr;
> + 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;
Should we only pickup these values if "anon_orders_configured",
otherwise start with 0? Likely that's implicit right now.
> + 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;
> +
> + nr = end - start + 1;
This only works as long as we don't have any "Holes", which is the case
right now.
> + if (!strcmp(policy, "always")) {
> + bitmap_set(&always, start, nr);
> + bitmap_clear(&inherit, start, nr);
> + bitmap_clear(&madvise, start, nr);
> + } else if (!strcmp(policy, "madvise")) {
> + bitmap_set(&madvise, start, nr);
> + bitmap_clear(&inherit, start, nr);
> + bitmap_clear(&always, start, nr);
> + } else if (!strcmp(policy, "inherit")) {
> + bitmap_set(&inherit, start, nr);
> + bitmap_clear(&madvise, start, nr);
> + bitmap_clear(&always, start, nr);
> + } else if (!strcmp(policy, "never")) {
> + bitmap_clear(&inherit, start, nr);
> + bitmap_clear(&madvise, start, nr);
> + bitmap_clear(&always, start, nr);
> + } 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);
"cannot parse, ignored" -> "error parsing string, ignoring setting" ?
> + 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))
--
Cheers,
David / dhildenb
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