On Wed, Jul 6, 2022 at 5:06 PM Zach O'Keefe <zokeefe@xxxxxxxxxx> wrote:
>
> Add a tracepoint to expose mm, address, and enum scan_result of each
> hugepage attempted to be collapsed by call to madvise(MADV_COLLAPSE).
Is this necessary? Isn't mm_khugepaged_scan_pmd tracepoint good
enough? It doesn't have "address", but you should be able to calculate
address from it with syscall trace together.
>
> Signed-off-by: Zach O'Keefe <zokeefe@xxxxxxxxxx>
> ---
> include/trace/events/huge_memory.h | 22 ++++++++++++++++++++++
> mm/khugepaged.c | 2 ++
> 2 files changed, 24 insertions(+)
>
> diff --git a/include/trace/events/huge_memory.h b/include/trace/events/huge_memory.h
> index 55392bf30a03..38d339ffdb16 100644
> --- a/include/trace/events/huge_memory.h
> +++ b/include/trace/events/huge_memory.h
> @@ -167,5 +167,27 @@ TRACE_EVENT(mm_collapse_huge_page_swapin,
> __entry->ret)
> );
>
> +TRACE_EVENT(mm_madvise_collapse,
> +
> + TP_PROTO(struct mm_struct *mm, unsigned long addr, int result),
> +
> + TP_ARGS(mm, addr, result),
> +
> + TP_STRUCT__entry(__field(struct mm_struct *, mm)
> + __field(unsigned long, addr)
> + __field(int, result)
> + ),
> +
> + TP_fast_assign(__entry->mm = mm;
> + __entry->addr = addr;
> + __entry->result = result;
> + ),
> +
> + TP_printk("mm=%p addr=%#lx result=%s",
> + __entry->mm,
> + __entry->addr,
> + __print_symbolic(__entry->result, SCAN_STATUS))
> +);
> +
> #endif /* __HUGE_MEMORY_H */
> #include <trace/define_trace.h>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index e0d00180512c..0207fc0a5b2a 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -2438,6 +2438,8 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
> if (!mmap_locked)
> *prev = NULL; /* Tell caller we dropped mmap_lock */
>
> + trace_mm_madvise_collapse(mm, addr, result);
> +
> switch (result) {
> case SCAN_SUCCEED:
> case SCAN_PMD_MAPPED:
> --
> 2.37.0.rc0.161.g10f37bed90-goog
>
