On Wed, Nov 25, 2015 at 09:41:12PM +0800, zhongjiang wrote: > This patch add the interface to show the number of 4KB or 64KB page, > aims to statistics the number of different types of pages.
What is this useful for? Why do we want it? What does it account for, just the swapper? > Signed-off-by: zhongjiang <[email protected]> > --- > arch/arm64/include/asm/pgtable-types.h | 24 ++++++++++++++++++++++++ > arch/arm64/mm/mmu.c | 28 ++++++++++++++++++++++++++++ > arch/arm64/mm/pageattr.c | 31 +++++++++++++++++++++++++++++++ > 3 files changed, 83 insertions(+), 0 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable-types.h > b/arch/arm64/include/asm/pgtable-types.h > index 2b1bd7e..aa52546 100644 > --- a/arch/arm64/include/asm/pgtable-types.h > +++ b/arch/arm64/include/asm/pgtable-types.h > @@ -86,6 +86,30 @@ typedef pteval_t pgprot_t; > > #endif /* STRICT_MM_TYPECHECKS */ > > +struct seq_file; > +extern void arch_report_meminfo(struct seq_file *m); > + > +enum pg_level { > + PG_LEVEL_NONE, > +#ifdef CONFIG_ARM64_4K_PAGES > + PG_LEVEL_4K, > + PG_LEVEL_2M, > + PG_LEVEL_1G, > +#else > + PG_LEVEL_64K, > + PG_LEVEL_512M, > +#endif > + PG_LEVEL_NUM > +}; This doesn't account for 16K pages, and it means each call site has to handle the various page sizes directly. It would be better to simply count PTE/PMD/PUD/PGD, then handle the size conversion at the end when logging. > @@ -85,6 +86,11 @@ void split_pmd(pmd_t *pmd, pte_t *pte) > set_pte(pte, pfn_pte(pfn, prot)); > pfn++; > } while (pte++, i++, i < PTRS_PER_PTE); > +#ifdef CONFIG_ARM64_4K_PAGES > + split_page_count(PG_LEVEL_2M); > +#else > + split_page_count(PG_LEVEL_512M); > +#endif > } e.g. here you'd just count PG_LEVEL_PMD, which would work regardless of page size. > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index 7a5ff11..c1888b9 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -15,12 +15,43 @@ > #include <linux/module.h> > #include <linux/sched.h> > > +#include <linux/seq_file.h> > #include <asm/pgalloc.h> > #include <asm/pgtable.h> > #include <asm/tlbflush.h> > > #include "mm.h" > > +static unsigned long direct_pages_count[PG_LEVEL_NUM]; This doesn't match reality by the time we start executing the kernel, given we created page tables in head.S. > + > +void update_page_count(int level, unsigned long pages) > +{ > + direct_pages_count[level] += pages; > +} > + > +void split_page_count(int level) > +{ > + direct_pages_count[level]--; > + direct_pages_count[level-1] += PTRS_PER_PTE; > +} > + > +void arch_report_meminfo(struct seq_file *m) > +{ > +#ifdef CONFIG_ARM64_4K_PAGES > + seq_printf(m, "DirectMap4k: %8lu kB\n", > + direct_pages_count[PG_LEVEL_4K] << 2); > + seq_printf(m, "DirectMap2M: %8lu kB\n", > + direct_pages_count[PG_LEVEL_2M] << 11); > + seq_printf(m, "DirectMap1G: %8lu kB\n", > + direct_pages_count[PG_LEVEL_1G] << 20); > +#else > + seq_printf(m, "DirectMap64k: %8lu kB\n", > + direct_pages_count[PG_LEVEL_64K] << 6); > + seq_printf(m, "DirectMap512M: %8lu kB\n", > + direct_pages_count[PG_LEVEL_512M] << 19); > +#endif > +} You could dynamuically determine the sizes here for each field, and not have to have #ifdefs. That all said, I don't see what this is useful for, and it looks very fragile. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
