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

Anshuman Khandual
2024-01-29T09:32:00Z

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@arm.com>
> ---
>
> 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",