Hi David, On 31/10/24 09:37, David Hildenbrand wrote:
On 30.10.24 13:58, Maíra Canal wrote:Add the ``thp_shmem=`` kernel command line to allow specifying thedefault policy of each supported shmem hugepage size. The kernel parameteraccepts the following format:thp_shmem=<size>[KMG],<size>[KMG]:<policy>;<size>[KMG]- <size>[KMG]:<policy>For example, thp_shmem=16K-64K:always;128K,512K:inherit;256K:advise;1M-2M:never;4M-8M:within_size By configuring the default policy of several shmem hugepages, the user can take advantage of mTHP before it's been configured through sysfs. Signed-off-by: Maíra Canal <mcanal@xxxxxxxxxx> --- .../admin-guide/kernel-parameters.txt | 10 ++ Documentation/admin-guide/mm/transhuge.rst | 17 +++ mm/shmem.c | 109 +++++++++++++++++- 3 files changed, 135 insertions(+), 1 deletion(-)
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diff --git a/mm/shmem.c b/mm/shmem.c index dfcc88ec6e34..c2299fa0b345 100644 --- a/mm/shmem.c +++ b/mm/shmem.c@@ -136,6 +136,7 @@ static unsigned long huge_shmem_orders_always __read_mostly;static unsigned long huge_shmem_orders_madvise __read_mostly; static unsigned long huge_shmem_orders_inherit __read_mostly; static unsigned long huge_shmem_orders_within_size __read_mostly; +static bool shmem_orders_configured __initdata; #endif #ifdef CONFIG_TMPFS @@ -5027,7 +5028,8 @@ void __init shmem_init(void)* Default to setting PMD-sized THP to inherit the global setting and* disable all other multi-size THPs. */ - huge_shmem_orders_inherit = BIT(HPAGE_PMD_ORDER); + if (!shmem_orders_configured) + huge_shmem_orders_inherit = BIT(HPAGE_PMD_ORDER); #endif return; @@ -5180,6 +5182,26 @@ struct kobj_attribute thpsize_shmem_enabled_attr = #if defined(CONFIG_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 (BIT(order) & ~THP_ORDERS_ALL_FILE_DEFAULT) + goto err; + + return order; +err: + pr_err("invalid size %s in thp_shmem boot parameter\n", size_str); + return -EINVAL; +}Hm, mostly copy and paste. You could reuse existing get_order_from_str() simply by passing in the supported orders and moving error reporting to the caller.
Can I use functions from mm/huge_memory.c here?
static inline int get_order_from_str(const char *size_str, int valid_orders) { ... if (!is_power_of_2(size)) return -EINVAL; order = get_order(size); if (BIT(order) & ~valid_orders) return -EINVAL; return order; }+ static int __init setup_transparent_hugepage_shmem(char *str) { int huge;@@ -5195,6 +5217,91 @@ static int __init setup_transparent_hugepage_shmem(char *str)}__setup("transparent_hugepage_shmem=", setup_transparent_hugepage_shmem);+static char str_dup[PAGE_SIZE] __initdata; +static int __init setup_thp_shmem(char *str) +{ + char *token, *range, *policy, *subtoken; + unsigned long always, inherit, madvise, within_size; + char *start_size, *end_size; + int start, end, nr; + char *p; + + if (!str || strlen(str) + 1 > PAGE_SIZE) + goto err; + strscpy(str_dup, str); + + always = huge_shmem_orders_always; + inherit = huge_shmem_orders_inherit; + madvise = huge_shmem_orders_madvise; + within_size = huge_shmem_orders_within_size; + 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; + if (!strcmp(policy, "always")) { + bitmap_set(&always, start, nr); + bitmap_clear(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + bitmap_clear(&within_size, start, nr); + } else if (!strcmp(policy, "advise")) { + bitmap_set(&madvise, start, nr); + bitmap_clear(&inherit, start, nr); + bitmap_clear(&always, start, nr); + bitmap_clear(&within_size, start, nr); + } else if (!strcmp(policy, "inherit")) { + bitmap_set(&inherit, start, nr); + bitmap_clear(&madvise, start, nr); + bitmap_clear(&always, start, nr); + bitmap_clear(&within_size, start, nr); + } else if (!strcmp(policy, "within_size")) { + bitmap_set(&within_size, start, nr); + bitmap_clear(&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); + bitmap_clear(&within_size, start, nr); + } else {+ pr_err("invalid policy %s in thp_shmem boot parameter\n", policy);+ goto err; + } + } + }Similarly, copy-paste. But not that easy to abstract :) So maybe we'll have to keep that as is for now.
On v2 [1], I abstracted to reduce copy and paste, but me and Barry agreed that adding this sort of header to linux/huge_mm.h was weird.[1] https://lore.kernel.org/linux-mm/20241029002324.1062723-4-mcanal@xxxxxxxxxx/
Best Regards, - Maíra
