Re: [PATCH 3/4] dma-debug: Dynamically expand the dma_debug_entry pool

[John Garry]

> > > In fact, having got this far in, what I'd quite like to do is to get rid
> > > of dma_debug_resize_entries() such that we never need to free things at
> > > all, since then we could allocate whole pages as blocks of entries to
> > > save on masses of individual slab allocations.
> >
> > On a related topic, is it possible for the user to learn the total
> > entries created at a given point in time? If not, could we add a file
> > in the debugfs folder for this?

Hi Robin,

> I did get as far as pondering that you effectively lose track of
> utilisation once the low-water-mark of min_free_entries hits 0 and stays

I did try your patches and I noticed this, i.e I was hitting the point 
at which we start to alloc more entries.

> there - AFAICS it should be sufficient to just expose nr_total_entries
> as-is, since users can then calculate current and maximum occupancy
> based on *_free_entries. Does that sound reasonable to you?

Sounds ok. I am just interested to know roughly how many DMA buffers 
we're using in our system.

> That also indirectly reminds me that this lot is documented in
> DMA_API.txt, so I should be good and update that too...

Thanks,
John

> Cheers,
> Robin.
>
> .