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

Alexandru Elisei
2024-01-29T11:53:45Z

Hi,

On Mon, Jan 29, 2024 at 03:01:24PM +0530, Anshuman Khandual wrote:
>
>
> 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.

Added for parity and because it's useful for this series (see my reply to
the previous patch where I discuss how I've used the counters).

Thanks,
Alex

>
> >
> > 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",