Re: [RFC v3 1/3] mm: add tracepoint for scanning pages

["Kirill A. Shutemov" <kirill@shutemov.name>]

On Mon, Jul 13, 2015 at 11:28:02PM +0300, Ebru Akagunduz wrote:
> Using static tracepoints, data of functions is recorded.
> It is good to automatize debugging without doing a lot
> of changes in the source code.
> 
> This patch adds tracepoint for khugepaged_scan_pmd,
> collapse_huge_page and __collapse_huge_page_isolate.
> 
> Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Acked-by: Rik van Riel <riel@redhat.com>
> ---
> Changes in v2:
>  - Nothing changed
> 
> Changes in v3:
>  - Print page address instead of vm_start (Vlastimil Babka)
>  - Define constants to specify exact tracepoint result (Vlastimil Babka)
>  
> 
>  include/linux/mm.h                 |  18 ++++++
>  include/trace/events/huge_memory.h | 100 ++++++++++++++++++++++++++++++++
>  mm/huge_memory.c                   | 114 +++++++++++++++++++++++++++----------
>  3 files changed, 203 insertions(+), 29 deletions(-)
>  create mode 100644 include/trace/events/huge_memory.h
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7f47178..bf341c0 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -21,6 +21,24 @@
>  #include <linux/resource.h>
>  #include <linux/page_ext.h>
>  
> +#define MM_PMD_NULL		0
> +#define MM_EXCEED_NONE_PTE	3
> +#define MM_PTE_NON_PRESENT	4
> +#define MM_PAGE_NULL		5
> +#define MM_SCAN_ABORT		6
> +#define MM_PAGE_COUNT		7
> +#define MM_PAGE_LRU		8
> +#define MM_ANY_PROCESS		0
> +#define MM_VMA_NULL		2
> +#define MM_VMA_CHECK		3
> +#define MM_ADDRESS_RANGE	4
> +#define MM_PAGE_LOCK		2
> +#define MM_SWAP_CACHE_PAGE	6
> +#define MM_ISOLATE_LRU_PAGE	7
> +#define MM_ALLOC_HUGE_PAGE_FAIL	6
> +#define MM_CGROUP_CHARGE_FAIL	7
> +#define MM_COLLAPSE_ISOLATE_FAIL 5
> +

These magic numbers looks very random. What's logic behind?

-- 
 Kirill A. Shutemov

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