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s390/mm,vmemmap: use 1MB frames for vmemmap 

Use 1MB frames for vmemmap if EDAT1 is available in order to
reduce TLB pressure
Always use a 1MB frame even if its only partially needed for
struct pages. Otherwise we would end up with a mix of large
frame and page mappings, because vmemmap_populate gets called
for each section (256MB -> 3.5MB memmap) separately.
Worst case is that we would waste 512KB.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2012-10-17 12:18:05 +02:00 committed by Martin Schwidefsky
parent 18da236908
commit f7817968d0
1 changed files with 25 additions and 1 deletions
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26
arch/s390/mm/vmem.c
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@ -205,7 +205,7 @@ int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
start_addr = (unsigned long) start;
end_addr = (unsigned long) (start + nr);
for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
for (address = start_addr; address < end_addr;) {
pg_dir = pgd_offset_k(address);
if (pgd_none(*pg_dir)) {
pu_dir = vmem_pud_alloc();
@ -224,10 +224,33 @@ int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
pm_dir = pmd_offset(pu_dir, address);
if (pmd_none(*pm_dir)) {
#ifdef CONFIG_64BIT
/* Use 1MB frames for vmemmap if available. We always
* use large frames even if they are only partially
* used.
* Otherwise we would have also page tables since
* vmemmap_populate gets called for each section
* separately. */
if (MACHINE_HAS_EDAT1) {
void *new_page;
new_page = vmemmap_alloc_block(PMD_SIZE, node);
if (!new_page)
goto out;
pte = mk_pte_phys(__pa(new_page), PAGE_RW);
pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
pmd_val(*pm_dir) = pte_val(pte);
address = (address + PMD_SIZE) & PMD_MASK;
continue;
}
#endif
pt_dir = vmem_pte_alloc(address);
if (!pt_dir)
goto out;
pmd_populate(&init_mm, pm_dir, pt_dir);
} else if (pmd_large(*pm_dir)) {
address = (address + PMD_SIZE) & PMD_MASK;
continue;
}
pt_dir = pte_offset_kernel(pm_dir, address);
@ -240,6 +263,7 @@ int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
*pt_dir = pte;
}
address += PAGE_SIZE;
}
memset(start, 0, nr * sizeof(struct page));
ret = 0;