On Mon, Oct 28, 2024 at 6:10 PM Maíra Canal <mcanal@xxxxxxxxxx> wrote: > > Hi Barry, > > On 27/10/24 18:54, Barry Song wrote: > > On Mon, Oct 28, 2024 at 6:58 AM Maíra Canal <mcanal@xxxxxxxxxx> wrote: > >> > >> Add the ``thp_shmem=`` kernel command line to allow specifying the > >> default policy of each supported shmem hugepage size. The kernel parameter > >> accepts 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 huge pages, 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(-) > >> > > > > Hi Maíra, > > > >> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > >> index acabb04d0dd4..595fa096e28b 100644 > >> --- a/Documentation/admin-guide/kernel-parameters.txt > >> +++ b/Documentation/admin-guide/kernel-parameters.txt > >> @@ -6700,6 +6700,16 @@ > >> Force threading of all interrupt handlers except those > >> marked explicitly IRQF_NO_THREAD. > >> > >> + shmem_anon= [KNL] > >> + Format: <size>[KMG],<size>[KMG]:<policy>;<size>[KMG]-<size>[KMG]:<policy> > >> + Control the default policy of each hugepage size for the > >> + internal shmem mount. <policy> is one of policies available > >> + for the shmem mount ("always", "inherit", "never", "within_size", > >> + and "advise"). > >> + It can be used multiple times for multiple shmem THP sizes. > >> + See Documentation/admin-guide/mm/transhuge.rst for more > >> + details. > > > > I'm not sure this is the right name. How about "thp_shmem"? > > Oops, sorry about that. > > > > >> + > >> topology= [S390,EARLY] > >> Format: {off | on} > >> Specify if the kernel should make use of the cpu > >> diff --git a/Documentation/admin-guide/mm/transhuge.rst b/Documentation/admin-guide/mm/transhuge.rst > >> index 9b5b02c4d1ab..47e7fc30e22d 100644 > >> --- a/Documentation/admin-guide/mm/transhuge.rst > >> +++ b/Documentation/admin-guide/mm/transhuge.rst > >> @@ -332,6 +332,23 @@ allocation policy for the internal shmem mount by using the kernel parameter > >> seven valid policies for shmem (``always``, ``within_size``, ``advise``, > >> ``never``, ``deny``, and ``force``). > >> > >> +In the same manner as ``thp_anon`` controls each supported anonymous THP > >> +size, ``thp_shmem`` controls each supported shmem THP size. ``thp_shmem`` > >> +has the same format as ``thp_anon``, but also supports the policy > >> +``within_size``. > >> + > >> +``thp_shmem=`` may be specified multiple times to configure all THP sizes > >> +as required. If ``thp_shmem=`` is specified at least once, any shmem THP > >> +sizes not explicitly configured on the command line are implicitly set to > >> +``never``. > >> + > >> +``transparent_hugepage_shmem`` setting only affects the global toggle. If > >> +``thp_shmem`` is not specified, PMD_ORDER hugepage will default to > >> +``inherit``. However, if a valid ``thp_shmem`` setting is provided by the > >> +user, the PMD_ORDER hugepage policy will be overridden. If the policy for > >> +PMD_ORDER is not defined within a valid ``thp_shmem``, its policy will > >> +default to ``never``. > >> + > >> Hugepages in tmpfs/shmem > >> ======================== > >> > >> diff --git a/mm/shmem.c b/mm/shmem.c > >> index 24cdeafd8260..0a7a7d04f725 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 > >> @@ -5013,7 +5014,8 @@ 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; > >> > >> @@ -5174,6 +5176,26 @@ 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; > >> +} > >> + > >> static int __init setup_transparent_hugepage_shmem(char *str) > >> { > >> int huge, ret = 0; > >> @@ -5206,6 +5228,91 @@ 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; > >> + strcpy(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; > >> + } > >> + } > >> + } > >> + > >> + huge_shmem_orders_always = always; > >> + huge_shmem_orders_madvise = madvise; > >> + huge_shmem_orders_inherit = inherit; > >> + huge_shmem_orders_within_size = within_size; > >> + shmem_orders_configured = true; > >> + return 1; > >> + > >> +err: > >> + pr_warn("thp_shmem=%s: error parsing string, ignoring setting\n", str); > >> + return 0; > >> +} > > > > Can we share source code with thp_anon since there's a lot of duplication? > > I'm not a regular mm contributor and I'm most usually around drivers, so > I don't know exactly here I could add shared code. Should I add the > headers to "internal.h"? My comment isn't related to drivers or memory management. It's solely about avoiding code duplication. For example, we could create a shared function to handle both controls, reducing redundant code :-) > > Best Regards, > - Maíra > > > > >> +__setup("thp_shmem=", setup_thp_shmem); > >> + > >> #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > >> > >> #else /* !CONFIG_SHMEM */ > >> -- > >> 2.46.2 > >> > > > > Thanks > > barry >