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SubjectRe: [PATCH] [7/7] CPA: Add statistics about state of direct mapping v2
On Wed, 12 Mar 2008, Andi Kleen wrote:
> Add information about the mapping state of the direct mapping to
> /proc/meminfo.

Please use debugfs for this.

> This way we can see how many large pages are really used for it and how
> many are split.
>
> Useful for debugging and general insight into the kernel.
>
> v2: Add hotplug locking to 64bit to plug a very obscure theoretical race.
> 32bit doesn't need it because it doesn't support hotadd for lowmem.
> Fix some typos
>
> Signed-off-by: Andi Kleen <ak@suse.de>
>
> ---
> arch/x86/mm/init_32.c | 2 ++
> arch/x86/mm/init_64.c | 2 ++
> arch/x86/mm/pageattr.c | 24 ++++++++++++++++++++++++
> fs/proc/proc_misc.c | 7 +++++++
> include/asm-x86/pgtable.h | 3 +++
> 5 files changed, 38 insertions(+)
>
> Index: linux/arch/x86/mm/init_64.c
> ===================================================================
> --- linux.orig/arch/x86/mm/init_64.c
> +++ linux/arch/x86/mm/init_64.c
> @@ -319,6 +319,8 @@ __meminit void early_iounmap(void *addr,
> static unsigned long __meminit
> phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end)
> {
> + unsigned long flags;
> + unsigned pages = 0;

Can we use unsigned long for both please and safe one line ?

> int i = pmd_index(address);
>
> for (; i < PTRS_PER_PMD; i++, address += PMD_SIZE) {
> @@ -335,9 +337,15 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
> if (pmd_val(*pmd))
> continue;
>
> + pages++;
> set_pte((pte_t *)pmd,
> pfn_pte(address >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
> }
> +
> + /* Protect against CPA */
> + spin_lock_irqsave(&pgd_lock, flags);
> + dpages_cnt[PG_LEVEL_2M] += pages;
> + spin_unlock_irqrestore(&pgd_lock, flags);

Please make the update a debugfs conditional function in the CPA
code. That way it can be compile out and the statistic internals are
not scattered all over the place.

> @@ -356,6 +364,8 @@ phys_pmd_update(pud_t *pud, unsigned lon
> static unsigned long __meminit
> phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end)
> {
> + unsigned long flags;
> + unsigned pages = 0;
> unsigned long true_end = end;

See above.

> int i = pud_index(addr);
>
> @@ -380,6 +390,7 @@ phys_pud_init(pud_t *pud_page, unsigned
> }
>
> if (direct_gbpages) {
> + dpages_cnt[PG_LEVEL_1G]++;
> set_pte((pte_t *)pud,
> pfn_pte(addr >> PAGE_SHIFT, PAGE_KERNEL_LARGE));
> true_end = (addr & PUD_MASK) + PUD_SIZE;
> @@ -397,6 +408,11 @@ phys_pud_init(pud_t *pud_page, unsigned
> }
> __flush_tlb_all();
>
> + /* Protect against CPA */
> + spin_lock_irqsave(&pgd_lock, flags);
> + dpages_cnt[PG_LEVEL_1G] += pages;
> + spin_unlock_irqrestore(&pgd_lock, flags);
> +

See above

> return true_end >> PAGE_SHIFT;
> }
>
> Index: linux/arch/x86/mm/pageattr.c
> ===================================================================
> --- linux.orig/arch/x86/mm/pageattr.c
> +++ linux/arch/x86/mm/pageattr.c
> @@ -18,6 +18,8 @@
> #include <asm/pgalloc.h>
> #include <asm/proto.h>
>
> +unsigned long dpages_cnt[PG_LEVEL_NUM];

Can we have some intuitive name for that like direct_pages_stats, so
it's clear that it is debug/statistics info ?

> /*
> * The current flushing context - we pass it instead of 5 arguments:
> */
> @@ -499,6 +501,12 @@ static int split_large_page(pte_t *kpte,
> for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
> set_pte(&pbase[i], pfn_pte(pfn, ref_prot));
>
> + if (address >= (unsigned long)__va(0) &&
> + address < (unsigned long)__va(end_pfn_map << PAGE_SHIFT)) {
> + dpages_cnt[level]--;
> + dpages_cnt[level - 1] += PTRS_PER_PTE;

inline conditional on DEBUGFS please

> + }
> +
> /*
> * Install the new, split up pagetable. Important details here:
> *
> @@ -948,6 +956,22 @@ bool kernel_page_present(struct page *pa
>
> #endif /* CONFIG_DEBUG_PAGEALLOC */
>
> +#ifdef CONFIG_PROC_FS

debugfs please

Thanks,

tglx


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