Commit f7817968 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
Browse files

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: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 18da2369

arch/s390/mm/vmem.c

+25 −1
Original line number Diff line number Diff line
@@ -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;

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