On 22/07/2024 10:36, Ryan Roberts wrote: > On 22/07/2024 10:13, Daniel Gomez wrote: >> On Wed, Jul 17, 2024 at 08:12:55AM GMT, Ryan Roberts wrote: >>> 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>[KMG]:<value> >> >> Minor suggestion. Should this be renamed to hp_anon= or hugepages_anon= instead? >> This would align with the values under /sys/kernel/mm/transparent_hugepage/ >> hugepages-*kB. > > "hp" doesn't feel right; that's not an abreviation we use today to my knowledge. > But I'd be happy to change it to "hugepages_anon", if that's the concensus. Thinking about this a bit more, "hugepages=" is already a cmdline parameter used to reserve hugepages for use with HugeTLB. So I think that could get confusing. transparent_hugepage= is the existing cmdline parameter for the top-level (anon) control. I considered "transparent_hugepage_anon=" or even just extending to use the same parameter for both the top level and the per-size controls (with optional size): transparent_hugepage=[<size>[KMG]:]<value> But given they likely need to be provided multiple times, both of those options seem too long. Which is how I settled on thp_anon= (and in the next patch, thp_file=). > >> >>> >>> 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@xxxxxxx> >>> --- >>> .../admin-guide/kernel-parameters.txt | 8 +++ >>> Documentation/admin-guide/mm/transhuge.rst | 26 +++++++-- >>> mm/huge_memory.c | 55 ++++++++++++++++++- >>> 3 files changed, 82 insertions(+), 7 deletions(-) >>> >>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt >>> index bc55fb55cd26..48443ad12e3f 100644 >>> --- a/Documentation/admin-guide/kernel-parameters.txt >>> +++ b/Documentation/admin-guide/kernel-parameters.txt >>> @@ -6592,6 +6592,14 @@ >>> <deci-seconds>: poll all this frequency >>> 0: no polling (default) >>> >>> + thp_anon= [KNL] >>> + Format: <size>[KMG]:always|madvise|never|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 1aaf8e3a0b5a..f53d43d986e2 100644 >>> --- a/Documentation/admin-guide/mm/transhuge.rst >>> +++ b/Documentation/admin-guide/mm/transhuge.rst >>> @@ -311,13 +311,27 @@ performance. >>> Note that any changes to the allowed set of sizes only applies to future >>> file-backed THP allocations. >>> >>> -Boot parameter >>> -============== >>> +Boot parameters >>> +=============== >>> >>> -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. >>> +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>[KMG]:<state>``, where ``<size>`` is the THP size >>> +and ``<state>`` is one of ``always``, ``madvise``, ``never`` or >>> +``inherit``. >>> + >>> +For example, the following will set 64K THP to ``always``:: >>> + >>> + thp_anon=64K:always >>> + >>> +``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``. >>> >>> Hugepages in tmpfs/shmem >>> ======================== >>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >>> index 4249c0bc9388..794d2790d90d 100644 >>> --- a/mm/huge_memory.c >>> +++ b/mm/huge_memory.c >>> @@ -82,6 +82,7 @@ unsigned long huge_anon_orders_madvise __read_mostly; >>> unsigned long huge_anon_orders_inherit __read_mostly; >>> unsigned long huge_file_orders_always __read_mostly; >>> int huge_file_exec_order __read_mostly = -1; >>> +static bool anon_orders_configured; >>> >>> unsigned long __thp_vma_allowable_orders(struct vm_area_struct *vma, >>> unsigned long vm_flags, >>> @@ -763,7 +764,10 @@ 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); >> >> PMD_ORDER for 64k base PS systems would result in a 512M value, which exceeds >> the xarray limit [1]. Therefore, I think we need to avoid PMD-size orders by >> checking if PMD_ORDER > MAX_PAGECACHE_ORDER. > > This is for anon memory, which isn't installed in the page cache so its > independent of MAX_PAGECACHE_ORDER. I don't believe there is a problem here. > >> >> [1] https://lore.kernel.org/all/20240627003953.1262512-1-gshan@xxxxxxxxxx/ >> >>> + anon_orders_configured = true; >>> + } >>> >>> /* >>> * For pagecache, default to enabling all orders. powerpc's PMD_ORDER >>> @@ -955,6 +959,55 @@ static int __init setup_transparent_hugepage(char *str) >>> } >>> __setup("transparent_hugepage=", setup_transparent_hugepage); >>> >>> +static int __init setup_thp_anon(char *str) >>> +{ >>> + unsigned long size; >>> + char *state; >>> + int order; >>> + int ret = 0; >>> + >>> + if (!str) >>> + goto out; >>> + >>> + size = (unsigned long)memparse(str, &state); >>> + order = ilog2(size >> PAGE_SHIFT); >>> + if (*state != ':' || !is_power_of_2(size) || size <= PAGE_SIZE || >>> + !(BIT(order) & THP_ORDERS_ALL_ANON)) >>> + goto out; >>> + >>> + state++; >>> + >>> + if (!strcmp(state, "always")) { >>> + clear_bit(order, &huge_anon_orders_inherit); >>> + clear_bit(order, &huge_anon_orders_madvise); >>> + set_bit(order, &huge_anon_orders_always); >>> + ret = 1; >>> + } else if (!strcmp(state, "inherit")) { >>> + clear_bit(order, &huge_anon_orders_always); >>> + clear_bit(order, &huge_anon_orders_madvise); >>> + set_bit(order, &huge_anon_orders_inherit); >>> + ret = 1; >>> + } else if (!strcmp(state, "madvise")) { >>> + clear_bit(order, &huge_anon_orders_always); >>> + clear_bit(order, &huge_anon_orders_inherit); >>> + set_bit(order, &huge_anon_orders_madvise); >>> + ret = 1; >>> + } else if (!strcmp(state, "never")) { >>> + clear_bit(order, &huge_anon_orders_always); >>> + clear_bit(order, &huge_anon_orders_inherit); >>> + clear_bit(order, &huge_anon_orders_madvise); >>> + ret = 1; >>> + } >>> + >>> + if (ret) >>> + anon_orders_configured = true; >>> +out: >>> + if (!ret) >>> + pr_warn("thp_anon=%s: cannot parse, ignored\n", str); >>> + return ret; >>> +} >>> +__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)) >>> -- >>> 2.43.0 >