Re: [PATCH RFC v3 07/35] mm: cma: Add CMA_RELEASE_{SUCCESS,FAIL} events

[Anshuman Khandual]

On 1/25/24 22:12, Alexandru Elisei wrote:
> Similar to the two events that relate to CMA allocations, add the
> CMA_RELEASE_SUCCESS and CMA_RELEASE_FAIL events that count when CMA pages
> are freed.

How is this is going to be beneficial towards analyzing CMA alloc/release
behaviour - particularly with respect to this series. OR just adding this
from parity perspective with CMA alloc side counters ? Regardless this
CMA change too could be discussed separately.

> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
> ---
> 
> Changes since rfc v2:
> 
> * New patch.
> 
>  include/linux/vm_event_item.h | 2 ++
>  mm/cma.c                      | 6 +++++-
>  mm/vmstat.c                   | 2 ++
>  3 files changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> index 747943bc8cc2..aba5c5bf8127 100644
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -83,6 +83,8 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
>  #ifdef CONFIG_CMA
>  		CMA_ALLOC_SUCCESS,
>  		CMA_ALLOC_FAIL,
> +		CMA_RELEASE_SUCCESS,
> +		CMA_RELEASE_FAIL,
>  #endif
>  		UNEVICTABLE_PGCULLED,	/* culled to noreclaim list */
>  		UNEVICTABLE_PGSCANNED,	/* scanned for reclaimability */
> diff --git a/mm/cma.c b/mm/cma.c
> index dbf7fe8cb1bd..543bb6b3be8e 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -562,8 +562,10 @@ bool cma_release(struct cma *cma, const struct page *pages,
>  {
>  	unsigned long pfn;
>  
> -	if (!cma_pages_valid(cma, pages, count))
> +	if (!cma_pages_valid(cma, pages, count)) {
> +		count_vm_events(CMA_RELEASE_FAIL, count);
>  		return false;
> +	}
>  
>  	pr_debug("%s(page %p, count %lu)\n", __func__, (void *)pages, count);
>  
> @@ -575,6 +577,8 @@ bool cma_release(struct cma *cma, const struct page *pages,
>  	cma_clear_bitmap(cma, pfn, count);
>  	trace_cma_release(cma->name, pfn, pages, count);
>  
> +	count_vm_events(CMA_RELEASE_SUCCESS, count);
> +
>  	return true;
>  }
>  
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index db79935e4a54..eebfd5c6c723 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1340,6 +1340,8 @@ const char * const vmstat_text[] = {
>  #ifdef CONFIG_CMA
>  	"cma_alloc_success",
>  	"cma_alloc_fail",
> +	"cma_release_success",
> +	"cma_release_fail",
>  #endif
>  	"unevictable_pgs_culled",
>  	"unevictable_pgs_scanned",