Re: [PATCH v2] mm: vmstat: add cma statistics

[John Hubbard <jhubbard@nvidia.com>]

On 3/2/21 10:33, Minchan Kim wrote:
> Since CMA is used more widely, it's worth to have CMA
> allocation statistics into vmstat. With it, we could
> know how agressively system uses cma allocation and
> how often it fails.
> 
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
> * from v1 - https://lore.kernel.org/linux-mm/20210217170025.512704-1-minchan@kernel.org/
>    * change alloc_attempt with alloc_success - jhubbard
>    * item per line for vm_event_item - jhubbard
> 
>   include/linux/vm_event_item.h |  4 ++++
>   mm/cma.c                      | 12 +++++++++---
>   mm/vmstat.c                   |  4 ++++
>   3 files changed, 17 insertions(+), 3 deletions(-)
> 

Seems reasonable, and the diffs look good.

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
-- 
John Hubbard
NVIDIA

> diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
> index 18e75974d4e3..21d7c7f72f1c 100644
> --- a/include/linux/vm_event_item.h
> +++ b/include/linux/vm_event_item.h
> @@ -70,6 +70,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
>   #endif
>   #ifdef CONFIG_HUGETLB_PAGE
>   		HTLB_BUDDY_PGALLOC, HTLB_BUDDY_PGALLOC_FAIL,
> +#endif
> +#ifdef CONFIG_CMA
> +		CMA_ALLOC_SUCCESS,
> +		CMA_ALLOC_FAIL,
>   #endif
>   		UNEVICTABLE_PGCULLED,	/* culled to noreclaim list */
>   		UNEVICTABLE_PGSCANNED,	/* scanned for reclaimability */
> diff --git a/mm/cma.c b/mm/cma.c
> index 23d4a97c834a..04ca863d1807 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -435,13 +435,13 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
>   	int ret = -ENOMEM;
>   
>   	if (!cma || !cma->count || !cma->bitmap)
> -		return NULL;
> +		goto out;
>   
>   	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,
>   		 count, align);
>   
>   	if (!count)
> -		return NULL;
> +		goto out;
>   
>   	mask = cma_bitmap_aligned_mask(cma, align);
>   	offset = cma_bitmap_aligned_offset(cma, align);
> @@ -449,7 +449,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
>   	bitmap_count = cma_bitmap_pages_to_bits(cma, count);
>   
>   	if (bitmap_count > bitmap_maxno)
> -		return NULL;
> +		goto out;
>   
>   	for (;;) {
>   		mutex_lock(&cma->lock);
> @@ -506,6 +506,12 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
>   	}
>   
>   	pr_debug("%s(): returned %p\n", __func__, page);
> +out:
> +	if (page)
> +		count_vm_event(CMA_ALLOC_SUCCESS);
> +	else
> +		count_vm_event(CMA_ALLOC_FAIL);
> +
>   	return page;
>   }
>   
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 97fc32a53320..d8c32a33208d 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -1305,6 +1305,10 @@ const char * const vmstat_text[] = {
>   #ifdef CONFIG_HUGETLB_PAGE
>   	"htlb_buddy_alloc_success",
>   	"htlb_buddy_alloc_fail",
> +#endif
> +#ifdef CONFIG_CMA
> +	"cma_alloc_success",
> +	"cma_alloc_fail",
>   #endif
>   	"unevictable_pgs_culled",
>   	"unevictable_pgs_scanned",
>