Commit 71f74568 authored by Thomas Prescher's avatar Thomas Prescher Committed by Andrew Morton
Browse files

mm: hugetlb: add hugetlb_alloc_threads cmdline option 

Add a command line option that enables control of how many threads should
be used to allocate huge pages.

[akpm@linux-foundation.org: tidy up a comment]
Link: https://lkml.kernel.org/r/20250227-hugepage-parameter-v2-2-7db8c6dc0453@cyberus-technology.de


Signed-off-by: default avatarThomas Prescher <thomas.prescher@cyberus-technology.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c34b3ece

Documentation/admin-guide/kernel-parameters.txt

+9 −0
Original line number Diff line number Diff line
@@ -1882,6 +1882,15 @@ 
			Documentation/admin-guide/mm/hugetlbpage.rst.

			Format: size[KMG]



	hugepage_alloc_threads=

			[HW] The number of threads that should be used to

			allocate hugepages during boot. This option can be

			used to improve system bootup time when allocating

			a large amount of huge pages.

			The default value is 25% of the available hardware threads.



			Note that this parameter only applies to non-gigantic huge pages.



	hugetlb_cma=	[HW,CMA,EARLY] The size of a CMA area used for allocation

			of gigantic hugepages. Or using node format, the size

			of a CMA area per node can be specified.

Documentation/admin-guide/mm/hugetlbpage.rst

+10 −0
Original line number Diff line number Diff line
@@ -145,7 +145,17 @@ hugepages 


	It will allocate 1 2M hugepage on node0 and 2 2M hugepages on node1.

	If the node number is invalid,  the parameter will be ignored.

hugepage_alloc_threads

	Specify the number of threads that should be used to allocate hugepages

	during boot. This parameter can be used to improve system bootup time

	when allocating a large amount of huge pages.



	The default value is 25% of the available hardware threads.

	Example to use 8 allocation threads::



		hugepage_alloc_threads=8



	Note that this parameter only applies to non-gigantic huge pages.

default_hugepagesz

	Specify the default huge page size.  This parameter can

	only be specified once on the command line.  default_hugepagesz can

mm/hugetlb.c

+29 −4
Original line number Diff line number Diff line
@@ -85,6 +85,7 @@ static unsigned long __initdata default_hstate_max_huge_pages; 
static bool __initdata parsed_valid_hugepagesz = true;

static bool __initdata parsed_default_hugepagesz;

static unsigned int default_hugepages_in_node[MAX_NUMNODES] __initdata;

static unsigned long hugepage_allocation_threads __initdata;



static char hstate_cmdline_buf[COMMAND_LINE_SIZE] __initdata;

static int hstate_cmdline_index __initdata;
@@ -3607,8 +3608,6 @@ static unsigned long __init hugetlb_pages_alloc_boot(struct hstate *h) 
		.numa_aware	= true

	};



	unsigned int num_allocation_threads = max(num_online_cpus() / 4, 1);



	job.thread_fn	= hugetlb_pages_alloc_boot_node;

	job.start	= 0;

	job.size	= h->max_huge_pages;
@@ -3629,9 +3628,13 @@ static unsigned long __init hugetlb_pages_alloc_boot(struct hstate *h) 
	 * | cascade lake 192 cpus |   39s |   20s |   11s |   10s |    9s |

	 * +-----------------------+-------+-------+-------+-------+-------+

	 */

	if (hugepage_allocation_threads == 0) {

		hugepage_allocation_threads = num_online_cpus() / 4;

		hugepage_allocation_threads = max(hugepage_allocation_threads, 1);

	}



	job.max_threads	= num_allocation_threads;

	job.min_chunk	= h->max_huge_pages / num_allocation_threads;

	job.max_threads	= hugepage_allocation_threads;

	job.min_chunk	= h->max_huge_pages / hugepage_allocation_threads;

	padata_do_multithreaded(&job);



	return h->nr_huge_pages;
@@ -5000,6 +5003,28 @@ void __init hugetlb_bootmem_alloc(void) 
	__hugetlb_bootmem_allocated = true;

}



/*

 * hugepage_alloc_threads command line parsing.

 *

 * When set, use this specific number of threads for the boot

 * allocation of hugepages.

 */

static int __init hugepage_alloc_threads_setup(char *s)

{

	unsigned long allocation_threads;



	if (kstrtoul(s, 0, &allocation_threads) != 0)

		return 1;



	if (allocation_threads == 0)

		return 1;



	hugepage_allocation_threads = allocation_threads;



	return 1;

}

__setup("hugepage_alloc_threads=", hugepage_alloc_threads_setup);



static unsigned int allowed_mems_nr(struct hstate *h)

{

	int node;