This is a patch for virtual memmap on sparsemem against 2.6.19-rc2.
booted well on my Tiger4.
In this time, this is just a RFC. comments on patch and advises for benchmarking
is welcome. (memory hotplug case is not well handled yet.)
ia64's SPARSEMEM uses SPARSEMEM_EXTREME. This requires 2-level table lookup by
software for page_to_pfn()/pfn_to_page(). virtual memmap can remove that costs.
But will consume more TLBs.
For make patches simple, pfn_valid() uses sparsemem's logic.
- Kame
==
This patch maps sparsemem's *sparse* memmap into contiguous virtual address range
starting from virt_memmap_start.
By this, pfn_to_page, page_to_pfn can be implemented as
#define pfn_to_page(pfn) (virt_memmap_start + (pfn))
#define page_to_pfn(pg) (pg - virt_memmap_start)
Difference from ia64's VIRTUAL_MEMMAP are
* pfn_valid() uses sparsemem's logic.
* memmap is allocated per SECTION_SIZE, so there will be some of RESERVED pages.
* no holes in MAX_ORDER range. so HOLE_IN_ZONE=n here.
Todo
- fix vmalloc() case in memory hotadd. (maybe __get_vm_area() can be used.)
Signed-Off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
include/asm-generic/memory_model.h | 7 +++
include/linux/mmzone.h | 8 +++
mm/Kconfig | 8 +++
mm/sparse.c | 85 +++++++++++++++++++++++++++++++++++--
4 files changed, 104 insertions(+), 4 deletions(-)
Index: linux-2.6.19-rc2/mm/Kconfig
===================================================================
--- linux-2.6.19-rc2.orig/mm/Kconfig 2006-10-18 18:13:39.000000000 +0900
+++ linux-2.6.19-rc2/mm/Kconfig 2006-10-18 18:14:07.000000000 +0900
@@ -77,6 +77,14 @@
def_bool y
depends on !SPARSEMEM
+config VMEMMAP_SPARSEMEM
+ bool "memmap in virtual space"
+ default y
+ depends on SPARSEMEM && ARCH_VMEMMAP_SPARSEMEM_SUPPORT
+ help
+ If this option is selected, you can speed up some kernel execution.
+ But this consumes large amount of virtual memory area in kernel.
+
#
# Both the NUMA code and DISCONTIGMEM use arrays of pg_data_t's
# to represent different areas of memory. This variable allows
Index: linux-2.6.19-rc2/include/asm-generic/memory_model.h
===================================================================
--- linux-2.6.19-rc2.orig/include/asm-generic/memory_model.h 2006-09-20 12:42:06.000000000 +0900
+++ linux-2.6.19-rc2/include/asm-generic/memory_model.h 2006-10-18 18:14:07.000000000 +0900
@@ -47,6 +47,7 @@
})
#elif defined(CONFIG_SPARSEMEM)
+#ifndef CONFIG_VMEMMAP_SPARSEMEM
/*
* Note: section's mem_map is encorded to reflect its start_pfn.
* section[i].section_mem_map == mem_map's address - start_pfn;
@@ -62,6 +63,12 @@
struct mem_section *__sec = __pfn_to_section(__pfn); \
__section_mem_map_addr(__sec) + __pfn; \
})
+#else /* CONFIG_VMEMMAP_SPARSEMEM */
+
+#define __pfn_to_page(pfn) (virt_memmap_start + (pfn))
+#define __page_to_pfn(pg) ((unsigned long)((pg) - virt_memmap_start))
+
+#endif /* CONFIG_VMEMMAP_SPARSEMEM */
#endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
#ifdef CONFIG_OUT_OF_LINE_PFN_TO_PAGE
Index: linux-2.6.19-rc2/include/linux/mmzone.h
===================================================================
--- linux-2.6.19-rc2.orig/include/linux/mmzone.h 2006-10-18 18:13:39.000000000 +0900
+++ linux-2.6.19-rc2/include/linux/mmzone.h 2006-10-18 18:14:07.000000000 +0900
@@ -599,6 +599,14 @@
extern struct mem_section mem_section[NR_SECTION_ROOTS][SECTIONS_PER_ROOT];
#endif
+
+#ifdef CONFIG_VMEMMAP_SPARSEMEM
+extern struct page *virt_memmap_start;
+extern void init_vmemmap_sparsemem(void *addr);
+#else
+#define init_vmemmap_sparsemem(addr) do{}while(0)
+#endif
+
static inline struct mem_section *__nr_to_section(unsigned long nr)
{
if (!mem_section[SECTION_NR_TO_ROOT(nr)])
Index: linux-2.6.19-rc2/mm/sparse.c
===================================================================
--- linux-2.6.19-rc2.orig/mm/sparse.c 2006-09-20 12:42:06.000000000 +0900
+++ linux-2.6.19-rc2/mm/sparse.c 2006-10-19 16:58:06.000000000 +0900
@@ -9,7 +9,81 @@
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <asm/dma.h>
+#include <asm/pgalloc.h>
+#ifdef CONFIG_VMEMMAP_SPARSEMEM
+struct page *virt_memmap_start;
+EXPORT_SYMBOL_GPL(virt_memmap_start);
+
+void init_vmemmap_sparsemem(void *start_addr)
+{
+ virt_memmap_start = start_addr;
+}
+
+void *pte_alloc_vmemmap(int node)
+{
+ void *ret;
+ if (system_state == SYSTEM_BOOTING) {
+ ret = alloc_bootmem_pages_node(NODE_DATA(node), PAGE_SIZE);
+ } else {
+ ret = kmalloc_node(PAGE_SIZE, GFP_KERNEL, node);
+ memset(ret, 0 , PAGE_SIZE);
+ }
+ BUG_ON(!ret);
+ return ret;
+}
+/*
+ * At Hot-add, vmalloc'ed memmap will never call this.
+ * They have been already in suitable address.
+ * Called only when map is allocated by alloc_bootmem()/alloc_pages()
+ */
+static void map_virtual_memmap(unsigned long section, void *map, int node)
+{
+ unsigned long vmap_start, vmap_end, vmap;
+ unsigned long pfn;
+ void *pg;
+ pgd_t *pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+
+ BUG_ON (!virt_memmap_start);
+
+ pfn = section_nr_to_pfn(section);
+ vmap_start = (unsigned long)(virt_memmap_start + pfn);
+ vmap_end = (unsigned long)(vmap_start + sizeof(struct page) * PAGES_PER_SECTION);
+
+ for (vmap = vmap_start; vmap < vmap_end; vmap += PAGE_SIZE, map += PAGE_SIZE)
+ {
+ pgd = pgd_offset_k(vmap);
+ if (pgd_none(*pgd)) {
+ pg = pte_alloc_vmemmap(node);
+ pgd_populate(&init_mm, pgd, pg);
+ }
+ pud = pud_offset(pgd, vmap);
+ if (pud_none(*pud)) {
+ pg = pte_alloc_vmemmap(node);
+ pud_populate(&init_mm, pud, pg);
+ }
+ pmd = pmd_offset(pud, vmap);
+ if (pmd_none(*pmd)) {
+ pg = pte_alloc_vmemmap(node);
+ pmd_populate_kernel(&init_mm, pmd, pg);
+ }
+ pte = pte_offset_kernel(pmd, vmap);
+ if (pte_none(*pte))
+ set_pte(pte, pfn_pte(__pa(map) >> PAGE_SHIFT, PAGE_KERNEL));
+ }
+ return;
+}
+#else /* CONFIG_VMEMMAP_SPARSEMEM */
+
+static inline void map_virtual_memmap(unsigned long section, void *map, int nid)
+{
+ return;
+}
+
+#endif /* CONFIG_VMEMMAP_SPARSEMEM */
/*
* Permanent SPARSEMEM data:
*
@@ -175,13 +249,14 @@
}
static int sparse_init_one_section(struct mem_section *ms,
- unsigned long pnum, struct page *mem_map)
+ unsigned long pnum, struct page *mem_map, int nid)
{
if (!valid_section(ms))
return -EINVAL;
ms->section_mem_map &= ~SECTION_MAP_MASK;
ms->section_mem_map |= sparse_encode_mem_map(mem_map, pnum);
+ map_virtual_memmap(pnum, mem_map, nid);
return 1;
}
@@ -214,10 +289,11 @@
page = alloc_pages(GFP_KERNEL, get_order(memmap_size));
if (page)
goto got_map_page;
-
+#ifndef CONFIG_VMEMMAP_SPARSEMEM
ret = vmalloc(memmap_size);
if (ret)
goto got_map_ptr;
+#endif
return NULL;
got_map_page:
@@ -261,7 +337,8 @@
map = sparse_early_mem_map_alloc(pnum);
if (!map)
continue;
- sparse_init_one_section(__nr_to_section(pnum), pnum, map);
+ sparse_init_one_section(__nr_to_section(pnum), pnum, map,
+ sparse_early_nid(__nr_to_section(pnum)));
}
}
@@ -296,7 +373,7 @@
}
ms->section_mem_map |= SECTION_MARKED_PRESENT;
- ret = sparse_init_one_section(ms, section_nr, memmap);
+ ret = sparse_init_one_section(ms, section_nr, memmap, zone->zone_pgdat->node_id);
out:
pgdat_resize_unlock(pgdat, &flags);
-
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