Re: [PATCH v3 1/4] mm: cma: add trace events to debug physically-contiguous memory allocations

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Stefan Strogin <s.strogin@partner.samsung.com> writes:

> Add trace events for cma_alloc() and cma_release().
>
> Signed-off-by: Stefan Strogin <s.strogin@partner.samsung.com>
> ---
>  include/trace/events/cma.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++
>  mm/cma.c                   |  6 +++++
>  2 files changed, 63 insertions(+)
>  create mode 100644 include/trace/events/cma.h
>
> diff --git a/include/trace/events/cma.h b/include/trace/events/cma.h
> new file mode 100644
> index 0000000..3fe7a56
> --- /dev/null
> +++ b/include/trace/events/cma.h
> @@ -0,0 +1,57 @@
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM cma
> +
> +#if !defined(_TRACE_CMA_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_CMA_H
> +
> +#include <linux/types.h>
> +#include <linux/tracepoint.h>
> +
> +TRACE_EVENT(cma_alloc,
> +
> +	TP_PROTO(struct cma *cma, unsigned long pfn, int count),
> +
> +	TP_ARGS(cma, pfn, count),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, pfn)
> +		__field(unsigned long, count)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->pfn = pfn;
> +		__entry->count = count;
> +	),
> +
> +	TP_printk("pfn=%lu page=%p count=%lu\n",
> +		  __entry->pfn,
> +		  pfn_to_page(__entry->pfn),
> +		  __entry->count)
> +);
> +
> +TRACE_EVENT(cma_release,
> +
> +	TP_PROTO(struct cma *cma, unsigned long pfn, int count),
> +
> +	TP_ARGS(cma, pfn, count),
> +
> +	TP_STRUCT__entry(
> +		__field(unsigned long, pfn)
> +		__field(unsigned long, count)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->pfn = pfn;
> +		__entry->count = count;
> +	),
> +
> +	TP_printk("pfn=%lu page=%p count=%lu\n",
> +		  __entry->pfn,
> +		  pfn_to_page(__entry->pfn),
> +		  __entry->count)
> +);
> +
> +#endif /* _TRACE_CMA_H */
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/mm/cma.c b/mm/cma.c
> index 9e3d44a..3a63c96 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -23,6 +23,7 @@
>  #  define DEBUG
>  #endif
>  #endif
> +#define CREATE_TRACE_POINTS
>
>  #include <linux/memblock.h>
>  #include <linux/err.h>
> @@ -34,6 +35,7 @@
>  #include <linux/cma.h>
>  #include <linux/highmem.h>
>  #include <linux/io.h>
> +#include <trace/events/cma.h>
>
>  #include "cma.h"
>
> @@ -408,6 +410,9 @@ struct page *cma_alloc(struct cma *cma, int count, unsigned int align)
>  		start = bitmap_no + mask + 1;
>  	}
>
> +	if (page)
> +		trace_cma_alloc(cma, pfn, count);
> +
>  	pr_debug("%s(): returned %p\n", __func__, page);
>  	return page;
>  }
> @@ -440,6 +445,7 @@ bool cma_release(struct cma *cma, struct page *pages, int count)
>
>  	free_contig_range(pfn, count);
>  	cma_clear_bitmap(cma, pfn, count);
> +	trace_cma_release(cma, pfn, count);
>
>  	return true;

Are we interested only in successful allocation and release ? Should we also
have the trace point carry information regarding failure ?

-aneesh