Re: [PATCH rdma-next v1 1/4] IB/mlx5: Introduce ODP diagnostic counters

From: Leon Romanovsky <leon@kernel.org>
To: Jason Gunthorpe <jgg@mellanox.com>
Cc: Doug Ledford <dledford@redhat.com>,
	RDMA mailing list <linux-rdma@vger.kernel.org>,
	Erez Alfasi <ereza@mellanox.com>
Subject: Re: [PATCH rdma-next v1 1/4] IB/mlx5: Introduce ODP diagnostic counters
Date: Mon, 9 Sep 2019 12:40:10 +0300	[thread overview]
Message-ID: <20190909094010.GA6601@unreal> (raw)
In-Reply-To: <20190909084535.GB2843@mellanox.com>

On Mon, Sep 09, 2019 at 08:45:36AM +0000, Jason Gunthorpe wrote:
> On Fri, Aug 30, 2019 at 11:16:09AM +0300, Leon Romanovsky wrote:
> > From: Erez Alfasi <ereza@mellanox.com>
> >
> > Introduce ODP diagnostic counters and count the following
> > per MR within IB/mlx5 driver:
> >  1) Page faults:
> > 	Total number of faulted pages.
> >  2) Page invalidations:
> > 	Total number of pages invalidated by the OS during all
> > 	invalidation events. The translations can be no longer
> > 	valid due to either non-present pages or mapping changes.
> >  3) Prefetched pages:
> > 	When prefetching a page, page fault is generated
> > 	in order to bring the page to the main memory.
> > 	The prefetched pages counter will be updated
> > 	during a page fault flow only if it was derived
> > 	from prefetching operation.
> >
> > Signed-off-by: Erez Alfasi <ereza@mellanox.com>
> > Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
> >  drivers/infiniband/hw/mlx5/odp.c | 18 ++++++++++++++++++
> >  include/rdma/ib_umem_odp.h       | 14 ++++++++++++++
> >  2 files changed, 32 insertions(+)
> >
> > diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
> > index 905936423a03..b7c8a49ac753 100644
> > +++ b/drivers/infiniband/hw/mlx5/odp.c
> > @@ -287,6 +287,10 @@ void mlx5_ib_invalidate_range(struct ib_umem_odp *umem_odp, unsigned long start,
> >
> >  	ib_umem_odp_unmap_dma_pages(umem_odp, start, end);
> >
> > +	/* Count page invalidations */
> > +	ib_update_odp_stats(umem_odp, invalidations,
> > +			    ib_umem_odp_num_pages(umem_odp));
>
> This doesn't seem right, it should only count the number of pages that
> were actually removed from the mapping

Absolutely, It is my mistake, I think that I mislead Erez back then.

>
> > diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
> > index b37c674b7fe6..3359e34516da 100644
> > +++ b/include/rdma/ib_umem_odp.h
> > @@ -37,6 +37,12 @@
> >  #include <rdma/ib_verbs.h>
> >  #include <linux/interval_tree.h>
> >
> > +struct ib_odp_counters {
> > +	atomic64_t faults;
> > +	atomic64_t invalidations;
> > +	atomic64_t prefetched;
> > +};
> > +
> >  struct ib_umem_odp {
> >  	struct ib_umem umem;
> >  	struct ib_ucontext_per_mm *per_mm;
> > @@ -62,6 +68,11 @@ struct ib_umem_odp {
> >  	struct mutex		umem_mutex;
> >  	void			*private; /* for the HW driver to use. */
> >
> > +	/*
> > +	 * ODP diagnostic counters.
> > +	 */
> > +	struct ib_odp_counters odp_stats;
>
> This really belongs in the MR not the umem

Bu why? We have umem_odp, all our statistics calculations are done
in umem_odp level.

>
> >  	int notifiers_seq;
> >  	int notifiers_count;
> >  	int npages;
> > @@ -106,6 +117,9 @@ static inline size_t ib_umem_odp_num_pages(struct ib_umem_odp *umem_odp)
> >  	       umem_odp->page_shift;
> >  }
> >
> > +#define ib_update_odp_stats(umem_odp, counter_name, value)		    \
> > +	atomic64_add(value, &(umem_odp->odp_stats.counter_name))
>
> Missing brackets in a macro

I am doubt about that, because it is one to one replace and not "real" macro.

Thanks

>
> Jason