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Subject[RFC v3 1/3] mm: add tracepoint for scanning pages
On Tue, Jul 14, 2015 at 12:06:46AM +0300, Kirill A. Shutemov wrote:
> 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?
>
I defined them to specify reason of all success and failure cases
of the functions with tracepoint. Only 1 means success case.

All other values mean failure, I give consecutive numbers as
far as possible, and tried to avoid conflicts of different functions
those can be fail for same reason.

kind regards,
Ebru


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