Hi Barry, On 28/10/24 19:35, Barry Song wrote:
On Mon, Oct 28, 2024 at 7:34 PM Maíra Canal <mcanal@xxxxxxxxxx> wrote:Hi Barry, On 28/10/24 08:09, Barry Song wrote: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[...]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 :-)Let me rephrase it. I completely agree that we should avoid code duplication. I'm asking where is the best place to add the headers of the shared functions. "linux/shmem_fs.h" doesn't look appropriate to me, so I believe the remaining options would be "linux/huge_mm.h" or "internal.h".Both locations seem quite odd. I have a feeling that these boot command elements are purely internal, yet internal.h contains something that is actually 'external' to mm. The shared code isn't 'external' enough to belong in internal.h. I didn't realize that shmem has placed these controls in its own file; I thought they were also located in mm/huge_memory.c. Given the current situation, I would prefer to keep the code as it is and tolerate the code duplication. Unless we are going to place controls for shmem and other thp controls in one place, I feel your code is better than having a shared function either in internal.h or linux/huge_mm.h.
Sorry, I only catch your e-mail after sending v2. If possible, please, take a look on v2 [1] and let me know if you still prefer to duplicate the code.[1] https://lore.kernel.org/linux-mm/20241029002324.1062723-1-mcanal@xxxxxxxxxx/T/
Best Regards, - Maíra
I would like to know your opinion about those two options. Best Regards, - MaíraBest Regards, - Maíra+__setup("thp_shmem=", setup_thp_shmem); + #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ #else /* !CONFIG_SHMEM */ -- 2.46.2Thanks barry
