See also Documentation/networking/decnet.txt.
default_hugepagesz=
- [same as hugepagesz=] The size of the default
- HugeTLB page size. This is the size represented by
- the legacy /proc/ hugepages APIs, used for SHM, and
- default size when mounting hugetlbfs filesystems.
- Defaults to the default architecture's huge page size
- if not specified.
+ [HW] The size of the default HugeTLB page. This is
+ the size represented by the legacy /proc/ hugepages
+ APIs. In addition, this is the default hugetlb size
+ used for shmget(), mmap() and mounting hugetlbfs
+ filesystems. If not specified, defaults to the
+ architecture's default huge page size. Huge page
+ sizes are architecture dependent. See also
+ Documentation/admin-guide/mm/hugetlbpage.rst.
+ Format: size[KMG]
deferred_probe_timeout=
[KNL] Debugging option to set a timeout in seconds for
hugepages using the cma allocator. If enabled, the
boot-time allocation of gigantic hugepages is skipped.
- hugepages= [HW,X86-32,IA-64] HugeTLB pages to allocate at boot.
- hugepagesz= [HW,IA-64,PPC,X86-64] The size of the HugeTLB pages.
- On x86-64 and powerpc, this option can be specified
- multiple times interleaved with hugepages= to reserve
- huge pages of different sizes. Valid pages sizes on
- x86-64 are 2M (when the CPU supports "pse") and 1G
- (when the CPU supports the "pdpe1gb" cpuinfo flag).
+ hugepages= [HW] Number of HugeTLB pages to allocate at boot.
+ If this follows hugepagesz (below), it specifies
+ the number of pages of hugepagesz to be allocated.
+ If this is the first HugeTLB parameter on the command
+ line, it specifies the number of pages to allocate for
+ the default huge page size. See also
+ Documentation/admin-guide/mm/hugetlbpage.rst.
+ Format: <integer>
+
+ hugepagesz=
+ [HW] The size of the HugeTLB pages. This is used in
+ conjunction with hugepages (above) to allocate huge
+ pages of a specific size at boot. The pair
+ hugepagesz=X hugepages=Y can be specified once for
+ each supported huge page size. Huge page sizes are
+ architecture dependent. See also
+ Documentation/admin-guide/mm/hugetlbpage.rst.
+ Format: size[KMG]
hung_task_panic=
[KNL] Should the hung task detector generate panics.
be specified in bytes with optional scale suffix [kKmMgG]. The default huge
page size may be selected with the "default_hugepagesz=<size>" boot parameter.
+Hugetlb boot command line parameter semantics
+hugepagesz - Specify a huge page size. Used in conjunction with hugepages
+ parameter to preallocate a number of huge pages of the specified
+ size. Hence, hugepagesz and hugepages are typically specified in
+ pairs such as:
+ hugepagesz=2M hugepages=512
+ hugepagesz can only be specified once on the command line for a
+ specific huge page size. Valid huge page sizes are architecture
+ dependent.
+hugepages - Specify the number of huge pages to preallocate. This typically
+ follows a valid hugepagesz or default_hugepagesz parameter. However,
+ if hugepages is the first or only hugetlb command line parameter it
+ implicitly specifies the number of huge pages of default size to
+ allocate. If the number of huge pages of default size is implicitly
+ specified, it can not be overwritten by a hugepagesz,hugepages
+ parameter pair for the default size.
+ For example, on an architecture with 2M default huge page size:
+ hugepages=256 hugepagesz=2M hugepages=512
+ will result in 256 2M huge pages being allocated and a warning message
+ indicating that the hugepages=512 parameter is ignored. If a hugepages
+ parameter is preceded by an invalid hugepagesz parameter, it will
+ be ignored.
+default_hugepagesz - Specify the default huge page size. This parameter can
+ only be specified once on the command line. default_hugepagesz can
+ optionally be followed by the hugepages parameter to preallocate a
+ specific number of huge pages of default size. The number of default
+ sized huge pages to preallocate can also be implicitly specified as
+ mentioned in the hugepages section above. Therefore, on an
+ architecture with 2M default huge page size:
+ hugepages=256
+ default_hugepagesz=2M hugepages=256
+ hugepages=256 default_hugepagesz=2M
+ will all result in 256 2M huge pages being allocated. Valid default
+ huge page size is architecture dependent.
+
When multiple huge page sizes are supported, ``/proc/sys/vm/nr_hugepages``
indicates the current number of pre-allocated huge pages of the default size.
Thus, one can use the following command to dynamically allocate/deallocate
/* for command line parsing */
static struct hstate * __initdata parsed_hstate;
static unsigned long __initdata default_hstate_max_huge_pages;
-static unsigned long __initdata default_hstate_size;
static bool __initdata parsed_valid_hugepagesz = true;
+static bool __initdata parsed_default_hugepagesz;
/*
* Protects updates to hugepage_freelists, hugepage_activelist, nr_huge_pages,
err = hugetlb_sysfs_add_hstate(h, hugepages_kobj,
hstate_kobjs, &hstate_attr_group);
if (err)
- pr_err("Hugetlb: Unable to add hstate %s", h->name);
+ pr_err("HugeTLB: Unable to add hstate %s", h->name);
}
}
nhs->hstate_kobjs,
&per_node_hstate_attr_group);
if (err) {
- pr_err("Hugetlb: Unable to add hstate %s for node %d\n",
+ pr_err("HugeTLB: Unable to add hstate %s for node %d\n",
h->name, node->dev.id);
hugetlb_unregister_node(node);
break;
if (!hugepages_supported())
return 0;
- if (!size_to_hstate(default_hstate_size)) {
- if (default_hstate_size != 0) {
- pr_err("HugeTLB: unsupported default_hugepagesz %lu. Reverting to %lu\n",
- default_hstate_size, HPAGE_SIZE);
+ /*
+ * Make sure HPAGE_SIZE (HUGETLB_PAGE_ORDER) hstate exists. Some
+ * architectures depend on setup being done here.
+ */
+ hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
+ if (!parsed_default_hugepagesz) {
+ /*
+ * If we did not parse a default huge page size, set
+ * default_hstate_idx to HPAGE_SIZE hstate. And, if the
+ * number of huge pages for this default size was implicitly
+ * specified, set that here as well.
+ * Note that the implicit setting will overwrite an explicit
+ * setting. A warning will be printed in this case.
+ */
+ default_hstate_idx = hstate_index(size_to_hstate(HPAGE_SIZE));
+ if (default_hstate_max_huge_pages) {
+ if (default_hstate.max_huge_pages) {
+ char buf[32];
+
+ string_get_size(huge_page_size(&default_hstate),
+ 1, STRING_UNITS_2, buf, 32);
+ pr_warn("HugeTLB: Ignoring hugepages=%lu associated with %s page size\n",
+ default_hstate.max_huge_pages, buf);
+ pr_warn("HugeTLB: Using hugepages=%lu for number of default huge pages\n",
+ default_hstate_max_huge_pages);
+ }
+ default_hstate.max_huge_pages =
+ default_hstate_max_huge_pages;
}
-
- default_hstate_size = HPAGE_SIZE;
- hugetlb_add_hstate(HUGETLB_PAGE_ORDER);
- }
- default_hstate_idx = hstate_index(size_to_hstate(default_hstate_size));
- if (default_hstate_max_huge_pages) {
- if (!default_hstate.max_huge_pages)
- default_hstate.max_huge_pages = default_hstate_max_huge_pages;
}
hugetlb_cma_check();
parsed_hstate = h;
}
-static int __init hugetlb_nrpages_setup(char *s)
+/*
+ * hugepages command line processing
+ * hugepages normally follows a valid hugepagsz or default_hugepagsz
+ * specification. If not, ignore the hugepages value. hugepages can also
+ * be the first huge page command line option in which case it implicitly
+ * specifies the number of huge pages for the default size.
+ */
+static int __init hugepages_setup(char *s)
{
unsigned long *mhp;
static unsigned long *last_mhp;
+ if (!hugepages_supported()) {
+ pr_warn("HugeTLB: huge pages not supported, ignoring hugepages = %s\n", s);
+ return 0;
+ }
+
if (!parsed_valid_hugepagesz) {
- pr_warn("hugepages = %s preceded by "
- "an unsupported hugepagesz, ignoring\n", s);
+ pr_warn("HugeTLB: hugepages=%s does not follow a valid hugepagesz, ignoring\n", s);
parsed_valid_hugepagesz = true;
- return 1;
+ return 0;
}
+
/*
- * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter yet,
- * so this hugepages= parameter goes to the "default hstate".
+ * !hugetlb_max_hstate means we haven't parsed a hugepagesz= parameter
+ * yet, so this hugepages= parameter goes to the "default hstate".
+ * Otherwise, it goes with the previously parsed hugepagesz or
+ * default_hugepagesz.
*/
else if (!hugetlb_max_hstate)
mhp = &default_hstate_max_huge_pages;
mhp = &parsed_hstate->max_huge_pages;
if (mhp == last_mhp) {
- pr_warn("hugepages= specified twice without interleaving hugepagesz=, ignoring\n");
- return 1;
+ pr_warn("HugeTLB: hugepages= specified twice without interleaving hugepagesz=, ignoring hugepages=%s\n", s);
+ return 0;
}
if (sscanf(s, "%lu", mhp) <= 0)
return 1;
}
-__setup("hugepages=", hugetlb_nrpages_setup);
+__setup("hugepages=", hugepages_setup);
+/*
+ * hugepagesz command line processing
+ * A specific huge page size can only be specified once with hugepagesz.
+ * hugepagesz is followed by hugepages on the command line. The global
+ * variable 'parsed_valid_hugepagesz' is used to determine if prior
+ * hugepagesz argument was valid.
+ */
static int __init hugepagesz_setup(char *s)
{
unsigned long size;
+ struct hstate *h;
+
+ parsed_valid_hugepagesz = false;
+ if (!hugepages_supported()) {
+ pr_warn("HugeTLB: huge pages not supported, ignoring hugepagesz = %s\n", s);
+ return 0;
+ }
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
- parsed_valid_hugepagesz = false;
- pr_err("HugeTLB: unsupported hugepagesz %s\n", s);
+ pr_err("HugeTLB: unsupported hugepagesz=%s\n", s);
return 0;
}
- if (size_to_hstate(size)) {
- pr_warn("HugeTLB: hugepagesz %s specified twice, ignoring\n", s);
- return 0;
+ h = size_to_hstate(size);
+ if (h) {
+ /*
+ * hstate for this size already exists. This is normally
+ * an error, but is allowed if the existing hstate is the
+ * default hstate. More specifically, it is only allowed if
+ * the number of huge pages for the default hstate was not
+ * previously specified.
+ */
+ if (!parsed_default_hugepagesz || h != &default_hstate ||
+ default_hstate.max_huge_pages) {
+ pr_warn("HugeTLB: hugepagesz=%s specified twice, ignoring\n", s);
+ return 0;
+ }
+
+ /*
+ * No need to call hugetlb_add_hstate() as hstate already
+ * exists. But, do set parsed_hstate so that a following
+ * hugepages= parameter will be applied to this hstate.
+ */
+ parsed_hstate = h;
+ parsed_valid_hugepagesz = true;
+ return 1;
}
hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
+ parsed_valid_hugepagesz = true;
return 1;
}
__setup("hugepagesz=", hugepagesz_setup);
+/*
+ * default_hugepagesz command line input
+ * Only one instance of default_hugepagesz allowed on command line.
+ */
static int __init default_hugepagesz_setup(char *s)
{
unsigned long size;
+ parsed_valid_hugepagesz = false;
+ if (!hugepages_supported()) {
+ pr_warn("HugeTLB: huge pages not supported, ignoring default_hugepagesz = %s\n", s);
+ return 0;
+ }
+
+ if (parsed_default_hugepagesz) {
+ pr_err("HugeTLB: default_hugepagesz previously specified, ignoring %s\n", s);
+ return 0;
+ }
+
size = (unsigned long)memparse(s, NULL);
if (!arch_hugetlb_valid_size(size)) {
- pr_err("HugeTLB: unsupported default_hugepagesz %s\n", s);
+ pr_err("HugeTLB: unsupported default_hugepagesz=%s\n", s);
return 0;
}
- default_hstate_size = size;
+ hugetlb_add_hstate(ilog2(size) - PAGE_SHIFT);
+ parsed_valid_hugepagesz = true;
+ parsed_default_hugepagesz = true;
+ default_hstate_idx = hstate_index(size_to_hstate(size));
+
+ /*
+ * The number of default huge pages (for this size) could have been
+ * specified as the first hugetlb parameter: hugepages=X. If so,
+ * then default_hstate_max_huge_pages is set. If the default huge
+ * page size is gigantic (>= MAX_ORDER), then the pages must be
+ * allocated here from bootmem allocator.
+ */
+ if (default_hstate_max_huge_pages) {
+ default_hstate.max_huge_pages = default_hstate_max_huge_pages;
+ if (hstate_is_gigantic(&default_hstate))
+ hugetlb_hstate_alloc_pages(&default_hstate);
+ default_hstate_max_huge_pages = 0;
+ }
+
return 1;
}
__setup("default_hugepagesz=", default_hugepagesz_setup);
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