From: Muchun Song <songmuchun@bytedance.com>
To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de,
mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com,
dave.hansen@linux.intel.com, luto@kernel.org,
peterz@infradead.org, viro@zeniv.linux.org.uk,
akpm@linux-foundation.org, paulmck@kernel.org,
mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com,
rdunlap@infradead.org, oneukum@suse.com,
anshuman.khandual@arm.com, jroedel@suse.de,
almasrymina@google.com, rientjes@google.com, willy@infradead.org,
osalvador@suse.de, mhocko@suse.com, song.bao.hua@hisilicon.com,
david@redhat.com, naoya.horiguchi@nec.com,
joao.m.martins@oracle.com
Cc: duanxiongchun@bytedance.com, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-fsdevel@vger.kernel.org,
Muchun Song <songmuchun@bytedance.com>,
Miaohe Lin <linmiaohe@huawei.com>
Subject: [PATCH v17 6/9] mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap
Date: Thu, 25 Feb 2021 21:21:27 +0800 [thread overview]
Message-ID: <20210225132130.26451-7-songmuchun@bytedance.com> (raw)
In-Reply-To: <20210225132130.26451-1-songmuchun@bytedance.com>
Add a kernel parameter hugetlb_free_vmemmap to enable the feature of
freeing unused vmemmap pages associated with each hugetlb page on boot.
We disables PMD mapping of vmemmap pages for x86-64 arch when this
feature is enabled. Because vmemmap_remap_free() depends on vmemmap
being base page mapped.
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Barry Song <song.bao.hua@hisilicon.com>
Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
---
Documentation/admin-guide/kernel-parameters.txt | 14 ++++++++++++++
Documentation/admin-guide/mm/hugetlbpage.rst | 3 +++
arch/x86/mm/init_64.c | 8 ++++++--
include/linux/hugetlb.h | 19 +++++++++++++++++++
mm/hugetlb_vmemmap.c | 24 ++++++++++++++++++++++++
5 files changed, 66 insertions(+), 2 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 04545725f187..de91d54573c4 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1557,6 +1557,20 @@
Documentation/admin-guide/mm/hugetlbpage.rst.
Format: size[KMG]
+ hugetlb_free_vmemmap=
+ [KNL] When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set,
+ this controls freeing unused vmemmap pages associated
+ with each HugeTLB page. When this option is enabled,
+ we disable PMD/huge page mapping of vmemmap pages which
+ increase page table pages. So if a user/sysadmin only
+ uses a small number of HugeTLB pages (as a percentage
+ of system memory), they could end up using more memory
+ with hugetlb_free_vmemmap on as opposed to off.
+ Format: { on | off (default) }
+
+ on: enable the feature
+ off: disable the feature
+
hung_task_panic=
[KNL] Should the hung task detector generate panics.
Format: 0 | 1
diff --git a/Documentation/admin-guide/mm/hugetlbpage.rst b/Documentation/admin-guide/mm/hugetlbpage.rst
index 6988895d09a8..8abaeb144e44 100644
--- a/Documentation/admin-guide/mm/hugetlbpage.rst
+++ b/Documentation/admin-guide/mm/hugetlbpage.rst
@@ -153,6 +153,9 @@ default_hugepagesz
will all result in 256 2M huge pages being allocated. Valid default
huge page size is architecture dependent.
+hugetlb_free_vmemmap
+ When CONFIG_HUGETLB_PAGE_FREE_VMEMMAP is set, this enables freeing
+ unused vmemmap pages associated with each HugeTLB page.
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.
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 0435bee2e172..39f88c5faadc 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -34,6 +34,7 @@
#include <linux/gfp.h>
#include <linux/kcore.h>
#include <linux/bootmem_info.h>
+#include <linux/hugetlb.h>
#include <asm/processor.h>
#include <asm/bios_ebda.h>
@@ -1557,7 +1558,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
{
int err;
- if (end - start < PAGES_PER_SECTION * sizeof(struct page))
+ if ((is_hugetlb_free_vmemmap_enabled() && !altmap) ||
+ end - start < PAGES_PER_SECTION * sizeof(struct page))
err = vmemmap_populate_basepages(start, end, node, NULL);
else if (boot_cpu_has(X86_FEATURE_PSE))
err = vmemmap_populate_hugepages(start, end, node, altmap);
@@ -1585,6 +1587,8 @@ void register_page_bootmem_memmap(unsigned long section_nr,
pmd_t *pmd;
unsigned int nr_pmd_pages;
struct page *page;
+ bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) ||
+ is_hugetlb_free_vmemmap_enabled();
for (; addr < end; addr = next) {
pte_t *pte = NULL;
@@ -1610,7 +1614,7 @@ void register_page_bootmem_memmap(unsigned long section_nr,
}
get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);
- if (!boot_cpu_has(X86_FEATURE_PSE)) {
+ if (base_mapping) {
next = (addr + PAGE_SIZE) & PAGE_MASK;
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd))
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ce6533584eb7..78934e9aeab6 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -852,6 +852,20 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
}
#endif
+#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP
+extern bool hugetlb_free_vmemmap_enabled;
+
+static inline bool is_hugetlb_free_vmemmap_enabled(void)
+{
+ return hugetlb_free_vmemmap_enabled;
+}
+#else
+static inline bool is_hugetlb_free_vmemmap_enabled(void)
+{
+ return false;
+}
+#endif
+
#else /* CONFIG_HUGETLB_PAGE */
struct hstate {};
@@ -1005,6 +1019,11 @@ static inline void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr
pte_t *ptep, pte_t pte, unsigned long sz)
{
}
+
+static inline bool is_hugetlb_free_vmemmap_enabled(void)
+{
+ return false;
+}
#endif /* CONFIG_HUGETLB_PAGE */
static inline spinlock_t *huge_pte_lock(struct hstate *h,
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index f7ab3d99250a..7807ed6678e0 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c
@@ -169,6 +169,8 @@
* (last) level. So this type of HugeTLB page can be optimized only when its
* size of the struct page structs is greater than 2 pages.
*/
+#define pr_fmt(fmt) "HugeTLB: " fmt
+
#include "hugetlb_vmemmap.h"
/*
@@ -181,6 +183,28 @@
#define RESERVE_VMEMMAP_NR 2U
#define RESERVE_VMEMMAP_SIZE (RESERVE_VMEMMAP_NR << PAGE_SHIFT)
+bool hugetlb_free_vmemmap_enabled;
+
+static int __init early_hugetlb_free_vmemmap_param(char *buf)
+{
+ /* We cannot optimize if a "struct page" crosses page boundaries. */
+ if ((!is_power_of_2(sizeof(struct page)))) {
+ pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n");
+ return 0;
+ }
+
+ if (!buf)
+ return -EINVAL;
+
+ if (!strcmp(buf, "on"))
+ hugetlb_free_vmemmap_enabled = true;
+ else if (strcmp(buf, "off"))
+ return -EINVAL;
+
+ return 0;
+}
+early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param);
+
static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstate *h)
{
return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT;
--
2.11.0
next prev parent reply other threads:[~2021-02-25 13:27 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-25 13:21 [PATCH v17 0/9] Free some vmemmap pages of HugeTLB page Muchun Song
2021-02-25 13:21 ` [PATCH v17 1/9] mm: memory_hotplug: factor out bootmem core functions to bootmem_info.c Muchun Song
2021-03-03 2:45 ` Singh, Balbir
2021-03-04 4:26 ` Balbir Singh
2021-03-04 5:50 ` [External] " Muchun Song
2021-02-25 13:21 ` [PATCH v17 2/9] mm: hugetlb: introduce a new config HUGETLB_PAGE_FREE_VMEMMAP Muchun Song
2021-03-04 5:06 ` Balbir Singh
2021-02-25 13:21 ` [PATCH v17 3/9] mm: hugetlb: free the vmemmap pages associated with each HugeTLB page Muchun Song
2021-03-04 23:50 ` Singh, Balbir
2021-03-05 4:41 ` [External] " Muchun Song
2021-03-05 4:41 ` Muchun Song
2021-02-25 13:21 ` [PATCH v17 4/9] mm: hugetlb: alloc " Muchun Song
2021-03-01 5:29 ` Muchun Song
2021-03-01 5:29 ` Muchun Song
2021-03-03 2:03 ` Mike Kravetz
2021-03-03 3:36 ` [External] " Muchun Song
2021-03-05 8:55 ` Balbir Singh
2021-03-05 9:30 ` [External] " Muchun Song
2021-02-25 13:21 ` [PATCH v17 5/9] mm: hugetlb: set the PageHWPoison to the raw error page Muchun Song
2021-03-07 8:18 ` Balbir Singh
2021-03-07 8:39 ` [External] " Muchun Song
2021-02-25 13:21 ` Muchun Song [this message]
2021-02-25 13:21 ` [PATCH v17 7/9] mm: hugetlb: introduce nr_free_vmemmap_pages in the struct hstate Muchun Song
2021-02-25 13:21 ` [PATCH v17 8/9] mm: hugetlb: gather discrete indexes of tail page Muchun Song
2021-02-25 13:21 ` [PATCH v17 9/9] mm: hugetlb: optimize the code with the help of the compiler Muchun Song
2021-03-02 12:27 ` [PATCH v17 0/9] Free some vmemmap pages of HugeTLB page Chen Huang
2021-03-04 3:14 ` Singh, Balbir
2021-03-04 3:36 ` [External] " Muchun Song
2021-03-04 4:25 ` Balbir Singh
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